Field of Science

Validity of Electronically Published New Taxonomic Names Redux: Posting Accepted Manuscripts

Sorry to dredge this up again, but I'd really like some input here from my readers.  In the past there has been much discussion of how new taxonomic names (i.e. genera and species) published solely in electronic format do not meet the requirements of the ICZN, nor will they meet the requirements of the most recent draft of PhyloCode when it is finally enacted. Journals such as PLoSONE and Palaeontologica Electronica have averted this by providing hard copy as well. However, past discussion has only discussed articles that are officially published.

A new dinosaurian taxon currently hitting the blogosphere is a ceratopsian dinosaur on exhibit at the Sam Noble Museum of Natural History in Norman, OK.  Norman hosted the annual SVP meeting less than a decade ago and many of us got to see this monster up close, it is quite amazing.  A recent blog post on this manuscript over at Love in the Time of Chasmosaurs (one of the best dino news blogs out there IMO, and thus this is not a critique of that post or the site) states that this new specimen has been published this week in the journal Cretaceous Research. However, a visit to the journal website shows that this paper is not in the most recent paper copy of the journal, nor is it even a finished paper published online in advance of print.  Instead it is currently only an accepted manuscript and still has to go through the steps of being assigned to a journal issue, not to mention the final proof stage.  Thus this new taxonomic name is still pretty far out from the final publication stage.  How far?  Depends on the journal.  Back around this time in 2006 I had a proposed taxonomic name in a paper that had been in the "accepted" stage for almost a year!  Most of you probably know how that situation ended.  "Accepted" technically is "in press", but until it has been assigned to an issue and the proof stage has been passed there really is no guarantee that the paper will be published anytime soon. Furthermore, various aspects of the paper, including the name, could still change at this stage.

What is to stop someone from providing a really quick publication through a faster outlet (including unfortunately something purportedly called "lulu press")? Nothing except personal ethics of individual researchers and maybe the fear that if someone ever did something so unscrupulous (after having seen the accepted paper) they would get called out by their peers.  It seems like a risk to me, especially as this is a specimen that has been on public display for years and there are numerous photos out there.

Also, what if the authors themselves think of a name (genus and/or species) they like better than the current one?  At this stage they could still change it. Although they still get the credit for the new name, the old name technically would still be available for another specimen in the future and could cause confusion if someone decided to use it. This does happen. For example, Adamanasuchus was a name originally proposed for the animal now known as Vancleavea.  It was published first as a nomen nudum in a 1983 issue of Arizona Highways magazine.  Lucas et al 2006 have since used this name (currently valid) for an aetosaur from the same stratigraphic horizon and geographical location.

Furthermore, a purview through the list of "in press" papers at Cretaceous Research shows that this is not the only newly proposed taxonomic name hanging out there.  I understand that the journal provides these papers early as a "service" to the readers, but given the taxonomic rules we all abide by that provides the accepted name to the first published in PRINT, I feel that the journals are taking a chance on our hard work going into this research.  Sorry but a DOI reference still does not count.

I like readers opinions on this type of extreme early "publishing".  Am a sounding overly cautious?  Maybe, but I personally don't feel like getting burned twice nor seeing any other researcher burned as well. I you believe testimony given in my past case you might argue that having the name out early might have averted the whole situation; however, knowing the whole history of what really happened I'm not buying it and neither should you.

[P.S. I've mentioned Aetogate as an example of what could happen and really don't want this to degenerate into a discussion of that particular case.  What I really want to know is if people really think it is a good idea to put new taxonomic names out there in the accepted manuscript stage where they have no protection against the priority rules in taxonomic nomenclature].

Calmasuchus acri, a new Capitosaur from the Middle Triassic of Spain

Just when I had been thinking that things had been rather slow this year regarding Triassic temnospondyl studies:

Fortuny, J., Galobart, À, and C. De Santisteban. In  press. A new capitosaur from the Middle Triassic of Spain and the relationships within the Capitosauria. Acta Palaeontologica Polonica, available online 29 Dec 2010 doi:10.4202/app.2010.0025
Abstract - Capitosaurs were the largest and homogeneous group of Triassic temnospondyl amphibians with cosmopolitan distribution. However, their interrelationships are debated. The first capitosaur cranial remains found in the Iberian Peninsula were assigned to Parotosuchus; herein, a re-description of this material, together with information on other remains recovered from the same site, enables us to classify them as a new genus: Calmasuchus acri gen. et sp. nov. (Amphibia: Temnospondyli) from the early-to-middle Anisian (early Middle Triassic). This capitosaur had a combination of plesiomorphic and non-plesiomorphic characters, such as posterolaterally directed tabular horns, paired anterior palatal vacuities, and unique morphology of the lower jaw. By cladistic analysis, we propose a new phylogeny for the monophyletic capitosaurs. In the analysis, Capitosauria is supported by seven synapomorphies. Wetlugasaurus is the most basal member of the clade. The score of the Russian taxon Vladlenosaurus alexeyevi resulted in a clade including Odenwaldia and the latter taxa. The Madagascarian Edingerella is the sister taxon of Watsonisuchus. Finally, Calmasuchus acri, the new taxon described here, appears as a more derived form than Parotosuchus. The new genus is the sister taxon of the Cyclotosaurus-Tatrasuchus and Eryosuchus-Mastodonsaurus clades.

Triassic Mystery Fossil

Things are a bit slow news wise over the holidays and I have not done this for awhile, so here goes.  Any guesses on what this is?  Should be relatively easy I think.

All I Want for Christmas is a Lagerstätte like this one: Exceptional Preservation of the Middle Triassic Luoping Biota of China

This new paper has been getting a lot of attention already (here and here). It basically provides some preliminary discussion of a well preserved marine fossil assemblage from the Middle Triassic of China which is rich in invertebrates, plants, and vertebrates. A detailed community structure and food web is proposed and the presence of top predators (e.g., ichthyosaurs) suggests a full recovery of the ecosystem following the end Permian extinction.  Based on the photographs in the article (one reproduced below), the specimens from this site are absolutely suberb, and this biota should be actively researched for years to come. I just need to find a Chinle lakebed that was full of microbial mats.

Hu, S.-x,. Zhang, Q.-y., Chen, Z.-Q., Zhou, C.-y., Lü, T., Xie, T., Wen, W., Huang, J. -y.,  and M. J. Benton, 2010. The Luoping biota: exceptional preservation, and new evidence on the Triassic recovery from end-Permian mass extinction. Proceedings of the Royal Society: B (advance online publication) doi: 10.1098/rspb.2010.2235

Abstract - The timing and nature of biotic recovery from the devastating end-Permian mass extinction (252 Ma) are much debated. New studies in South China suggest that complex marine ecosystems did not become re-established until the middle–late Anisian (Middle Triassic), much later than had been proposed by some. The recently discovered exceptionally preserved Luoping biota from the Anisian Stage of the Middle Triassic, Yunnan Province and southwest China shows this final stage of community assembly on the continental shelf. The fossil assemblage is a mixture of marine animals, including abundant lightly sclerotized arthropods, associated with fishes, marine reptiles, bivalves, gastropods, belemnoids, ammonoids, echinoderms, brachiopods, conodonts and foraminifers, as well as plants and rare arthropods from nearby land. In some ways, the Luoping biota rebuilt the framework of the pre-extinction latest Permian marine ecosystem, but it differed too in profound ways. New trophic levels were introduced, most notably among top predators in the form of the diverse marine reptiles that had no evident analogues in the Late Permian. The Luoping biota is one of the most diverse Triassic marine fossil Lagerstätten in the world, providing a new and early window on recovery and radiation of Triassic marine ecosystems some 10 Myr after the end-Permian mass extinction.

There is more information here.

New Triassic Insect from Kyrgystan and a New Species of Palaeoxyris from Germany

Béthoux, O., Voigt, S., and J. W. Schneider. 2010. A Triassic palaeodictyopteran from Kyrgyzstan. Palaeodiversity 3: 9–13.

Abstract - A specimen belonging to the species reliquia n. sp. is described from the Dzaylyaucho locality (Madygen, Kyrgyzstan; late Middle to early Late Triassic). It is interpreted as a palaeodictyopteran. It is therefore the latest occurrence of this group, previously considered as extinct during Middle to earliest Late Permian.

Böttcher, R. 2010. Description of the shark egg capsule Palaeoxyris friessi n. sp. From the Ladinian (Middle Triassic) of SW Germany and discussion of all known egg capsules from the Triassic of the Germanic Basin. Palaeodiversity 3: 123–139.
Abstract - The new shark egg capsule Palaeoxyris friessi n. sp. is described from the Hauptsandstein of the Lower Keuper (Erfurt Formation, Ladinian, Middle Triassic). The type and only specimen is complete and remarkably well preserved. With a length of 27 cm it is the longest complete Palaeoxyris egg capsule known so far. It is interpreted as an egg capsule of the hybodontid sharks Polyacrodus polycyphus or cf. Polyacrodus keuperianus. The capsule is associated with a rich flora, the brackish water bivalve Unionites and conchostracans, but other vertebrate remains were absent. All known records of Triassic and Lower Jurassic egg capsules from the Germanic Basin and their potential producers are discussed. All of the capsules have been found in deltaic or prodeltaic deposits.

Chuxiongosaurus lufengensis, a New Basal Sauropod from the Early Jurassic of China

Lü J., Y. Kobayashi, Li T. & Zhong S., 2010. A new basal sauropod dinosaur from the Lufeng Basin, Yunnan Province, southwestern China. Acta Geologica Sinica 84: 1336-1342.

Abstract - A new dinosaur Chuxiongosaurus lufengensis gen. et sp. nov. is erected based on a nearly complete skull. The taxon is characterized by the lacrimal perpendicular to the ventral margin of the upper jaw, which is similar to that of Thecodontosaurus; a depression present on the dorsal profile of the snout behind the naris; the rostral profile of the maxilla slopes continuously towards the rostral tip; and the presence of 25 dentary teeth. It also displays prosauropod characters such as a relatively long skull, the slope of the maxillary rostral profile, and teeth that do not have basically constricted crowns. The new specimen is more basal than Anchisaurus and represents the first basal sauropod dinosaur from the Early Jurassic of China.

New Hypothesis on European Phytosaur Ecology

Before you read this new paper you should read this older one:

Nesbitt, S.J. and M.R. Stocker. 2008. The vertebrate assemblage of the Late Triassic Canjilon Quarry (Northern New Mexico, USA), and the importance of apomorphy-based assemblage comparisons. Journal of Vertebrate Paleontology 28:1063-1072.

I'm afraid that I don't find the identifications in this paper to be rigorously determined (see the Nesbitt and Stocker paper for further discussion) nor the ecological implications to be strongly supported, thus I have doubts about the overall findings in this paper.  I'm also not convinced that all phytosaur genera with robust and gracile morphs represent sexual dimorphs (as proposed in passing for Nicrosaurus and Mystriosuchus).  The data to support this (i.e. monotaxic bonebeds showing both morphs) simply do not exist with the possible exception of Pseudopalatus pristinus and P. buceros from the Canjilon Quarry (Chinle Formation) of New Mexico.   This quarry contains over a dozen skulls of robust and gracile morphs of these two species and has been interpreted first by Colbert (1947) and later by Ziegler et al (2002) as representing sexual dimorphs. Nonetheless the ecological criteria proposed in this new paper suggests different feeding strategies for the dimorphs (which have different dentitions), thus males and females would have different food sources (e.g., piscivorous vs. generalist).

Kimmig, J., and G. Arp. 2010. Phytosaur remains from the Norian Arnstadt Formation (Leine Valley, Germany), with reference to European phytosaur habitats. Palaeodiversity 3: 215–224.

Abstract - Most inferences on phytosaur ecology are based on comparisons with extant crocodilians, in particular with reference to similarities in their skull morphology. In addition, the sedimentary environment of their place of embedding provides information on their life habitat and the potential lifestyle of these animals. Here we report on newly discovered phytosaur remains from the Norian Arnstadt Formation, which support the interpretation that the European phytosaur genera Mystriosuchus and Nicrosaurus had different ecological preferences. While Mystriosuchus, similar to Paleorhinus, was semi-aquatic and piscivorous, Nicrosaurus had a terrestrial lifestyle and probably preyed on tetrapods. Comparing the habitats of the different European phytosaur genera reported in literature, it is also concluded, that Mystriosuchus and Paleorhinus tolerated, contrary to Nicrosaurus, a wide range of salinity.

New Data on the Early Triassic Land Flora Recovery

Yu, J., Broutin, J., Huang, Q., and L. Grauvogel-Stamm. 2010. Annalepis, a pioneering lycopsid genus in the recovery of the Triassic land flora in South China. Comptes Rendus Palevol 9:479-486. doi:10.1016/j.crpv.2010.09.004 Abstract - Fossil plants are scarce in the Earliest Triassic marine deposits of western Guizhou and eastern Yunnan. Only Annularia shirakii, Lobatannularia sp., Paracalamites stenocostatus, Gigantopteris sp., Pecopteris sp. were reported from the base of the Kayitou Formation dated as Early Induan by marine fauna. Recently, we discovered numerous representatives of the genus Annalepis in the same Lowermost Triassic beds: A. latiloba, A. brevicystis, A. angusta, Annalepis spp. occur associated with a basal Triassic marine fauna. This discovery fills the biostratigraphic gap between the Late Permian “Gigantonoclea guizhouensis-Ullmannia cf. bronnii-Annularia pingloensis” and the late Lower Triassic “Neuropteridium–Albertia–Voltzia” assemblages reported from South China. It represents an important datum dealing with the very beginning of a new terrestrial flora installation after the Permian flora disappearance following the Permian–Triassic boundary mass extinction. This “starting point” of a new vegetal cover in South China is to be taken into account in reconstructing through space and time the settlement process of the Mesozoic floristic provinces.

Pterosaurs are Archosauriforms

Nesbitt, S. J., and D. W. E. Hone. 2010. An external mandibular fenestra and other archosauriform character states in basal pterosaurs. Palaeodiversity 3: 225–233.

Abstract - Pterosauria, a successful clade of extinct flying vertebrates, possesses a radical body plan that offers few clues about their origin and closest relatives. Whereas most researchers hypothesize an origin within Archosauria as the sister-group to Dinosauromorpha, others favor a position among non archosauriform archosauromorphs. Here we present evidence that supports a placement within Archosauriformes: the presence of an external mandibular fenestra in two basal pterosaur taxa, Dimorphodon macronyx and a specimen referred to Eudimorphodon cf. ranzii (= ‘Seefeld Eudimorphodon’; BSP 1994 I 51). Furthermore, the arrangement of the mandibular bones surrounding the mandibular fenestra and the presence of a posterior process of the dentary that laterally overlaps the angular in the mandible of Dimorphodon and BSP 1994 I 51 are identical to those of Erythrosuchus, Euparkeria, and Archosauria. When mapped on a cladogram, presence or absence of an external mandibular fenestra in basal pterosaurs possibly indicates that the feature is primitive for Pterosauria but later lost. The presence of an external mandibular fenestra, along with morphological evidence elsewhere in the body of pterosaurs(serrated teeth, antorbital fossa present, fourth trochanter on the femur present), supports a placement of Pterosauria within Archosauriformes and is consistent with a position within Archosauria.

from Nesbitt & Hone 2010 - Palaeodiversitas 3

An Upclose Look at the Microanatomy of Aetosaur Osteoderms

Aetosaurs are characterized by their elaborate bony carapaces composed of numerous osteoderms.  In fact aetosaur taxonomy is almost based solely on the morphology (especially the surface ornamentation) of osteoderms.  Despite this detailed studies of the microstructure of aetosaur oseoderms are lacking.  In 2008 I published a paper with Michelle Stocker and Randall Irmis that provided the first histological data for aetosaur osteoderms, but we were mostly looking at providing an estimated age at time of death for the holotype of Sierritasuchus macalpini to determine the ontogenetic stage of the specimen.

This new study focuses on aetosaurine osteoderms from Argentina and Brazil, including specimens assigned to Aetosauroides scagliai. One of the very cool things these authors did was not only to look a parasaggital sections of the rectangular osteoderms, they also looked at transverse sections. Some of the key findings are as follows:

- Aetosaur osteoderms lend themselves well to this type of study as secondary remodeling is minimal.

-Unlike all other sampled archosaurs, aetosaur osteoderm ossification was not metaplastic in nature (i.e. pre-existing, fully developed tissue is ossified), instead the osteoderms seemingly underwent intermembraneous ossification where new tissue displaces preformed tissue rather than incorporating it.  This is currently unique among archosaurs.

- Cyclic growth lines (Lines of arrested growth of LAG's) are well developed. Based on this the specimens sampled belonged to a range of subadult animals between two and nine years of age at time of death (minimum ages).

- The center of ossification in aetosaur osteoderms is at the level of the raised dorsal eminence.

- Aetosaur plates probably grew by adding peripheral layers.  Interestingly most faster growth occurred along the medial and lateral margins.  This accounts for the assymetrical placement of the dorsal eminence that is characteristic of aetosaurines.

- Well-developed Sharpey's fibers along the medial and lateral margins of the osteoderms suggest strong lateral and medial attachments along a row of osteoderms.  In contrast the attachments with anterior of posterior plates were poor, presumably allowing for flexion and movement in the carapace.

-Finally, the ornamentation of the osteoderms is formed by local resorption and partitial redeposition of the cortical bone. Acceleration of growth in particular areas enhances the degree of sculpture through time and the pattern is established early and then maintained through future growth.  This is seemingly why the ornamentation in juvenile specimens does not differ significantly from that of adults. This is extremely significant if you are using this patterning to diagnose taxa.

Overall an important study and excellent paper.

Cerda, I. A., and J. B. Desojo. 2010: Dermal armour histology of aetosaurs (Archosauria: Pseudosuchia), from the Upper Triassic of Argentina and Brazil. Lethaia, DOI: 10.1111/j.1502-3931.2010.00252.x.

Abstract - One of the most striking features documented in aetosaurs is the presence of an extensive bony armour composed of several osteoderms. Here, we analyse the bone microstructure of these elements in some South American Aetosaurinae aetosaurs, including Aetosauroides scagliai. In general terms, Aetosaurinae osteoderms are compact structures characterized by the presence of three tissue types: a basal cortex of poorly vascularized parallel-fibred bone tissue, a core of highly vascularized fibro-lamellar bone, and an external cortex of rather avascular lamellar bone tissue. Sharpey’s fibres are more visible at the internal core, toward the lateral margins and aligned parallel to the major axis of the dermal plate. No evidence of metaplastic origin is reported in the osteoderms, and we hypothesize an intramembranous ossification for these elements. The bone tissue distribution reveals that the development of the osteoderm in Aetosaurinae starts in a position located medial to the plate midpoint, and the main sites of active osteogenesis occur towards the lateral and medial edges of the plate. The osteoderm ornamentation is originated and maintained by a process of resorption and redeposition of the external cortex, which also includes preferential bone deposition in some particular sites. Given that no secondary reconstruction occurs in the osteoderms, growth marks are well preserved and they provide very important information regarding the relative age and growth pattern of Aetosaurinae aetosaurs.

Pangean Great Lake Paleoecology on the Cusp of the End-Triassic Extinction

Very cool study of the fish community in a large scale lake responding to changing environmental conditions during the earliest Jurassic.

Whiteside, J. H., Olsen, P. E., Eglinton, T. I., Cornet, B., McDonald, N. G., and P. Huber. In press. Pangean great lake paleoecology on the cusp of the end-Triassic extinction. Palaeogeography (2010), doi:10.1016/j.palaeo.2010.11.025.

Abstract - Triassic and Early Jurassic age lacustrine deposits of eastern North American rift basins preserve a spectacular record of precession-related Milankovitch forcing in the Pangean tropics in the wake of the end-Triassic extinction event (ETE). The abundant and well preserved fossil fish assemblages from these great lakes show cyclical changes that track the permeating hierarchy of climatic cycles. To detail ecosystem processes correlating with succession of fish communities, bulk δ13C was measured through a 100 ky series of precession-forced lake level cycles in the lower Shuttle Meadow Formation of the Hartford rift basin, Connecticut that were deposited within 50 ky after the ETE. The deep-water phase of one of these cycles, the Bluff Head Bed, has produced thousands of articulated fish. There are fluctuations in the bulk δ13Corg in the cyclical strata that reflect differing degrees of lake water stratification, nutrient levels, and relative proportion of algal vs. plant derived organic matter that trace fish community changes. Extrinsic changes in the global exchangeable reservoirs can be excluded as an origin of this variability because molecule-level δ13C of n-alkanes from plant leaf waxes in the same strata show no such variability. Although higher taxonomic levels of the fish communities responded largely by sorting of taxa by environmental forcing, at the species level the holostean genus Semionotus responded by in situ evolution, and ultimately extinction, of a species flock. Fluctuations at the higher frequency, climatic precessional scale are mirrored at lower frequency, eccentricity modulated, scales, all following the lake-level hierarchical pattern. Thus, changes in lacustrine isotopic ratios amplify the Milankovitch climate signal that was already intensified by sequelae of the end-Triassic extinctions. The degree to which the ecological structure of modern lakes responds to similar environmental cyclicity is largely unknown, but similar patterns and processes are present within the Neogene history of the East African great lakes.

Surprise! Scientists now say that Crocodiles are not "Living Fossils".

Here are some excerpts from a BBC article that was posted online today:

"Crocodiles can no longer be referred to as "living fossils", according to scientists".

"Members of the crocodilian [sic] family have previously been thought to have changed little since prehistoric times. However, new fossil analyses suggests that modern crocodilians actually evolved from a very diverse group".

"Recently discovered ancient ancestors include small cat-like specimens, giant "supercrocs" and a pug-nosed vegetarian species".

"Modern crocodilians are adapted to aquatic environments with long snouts, strong tails and powerful jaws. Yet contrary to popular belief, scientists now suggest that the basic body structure of crocodiles, alligators and ghariels [sic] evolved from a diverse group of prehistoric reptiles with different body shapes".

You can read the rest of this story here.  I am always flabbergasted how these "popular beliefs" still persist and how this "revelation" can be considered new.

Can't wait to get my copy of the new JVP memoir though.  It sounds incredible.

Two New Cynodont Papers from the Middle Triassic of Gondwana

The first paper is a short note so there is no abstract.

Kammerer, C. F., Flynn, J. J., Ranivoharimanana, L. and A. R. Wyss. 2010. The first record of a probainognathian (Cynodontia: Chiniquodontidae) from the Triassic of Madagascar. Journal of Vertebrate Paleontology 30:1889-1894. DOI: 10.1080/02724634.2010.520784

Note: The authors state that this specimen is probably Middle Triassic in age, but could possibly be as young as Carnian.

Martinelli, A. G. 2010. On the postcanine dentition of Pascualgnathus polanskii Bonaparte (Cynodontia, Traversodontidae) from the Middle Triassic of Argentina. Geobios 43:629–638

Abstract - The dental morphology of Pascualgnathus polanskii Bonaparte (Therapsida, Eucynodontia, Traversodontidae), from the Middle Triassic Río Seco de la Quebrada Formation (Puesto Viejo Group, Argentina), is described and compared with that of other basal traversodontid cynodonts. Albeit Pascualgnathus is frequently used in phylogenetic analyses, neither a detailed description nor drawings of its postcanines have been published so far. The upper postcanines of Pascualgnathus are transversely wide, rectangular in occlusal view, with a lingual cusp connected to the transverse ridge which is located in the center of the crown, and one main labial cusp followed by one posterior labial, both forming the labial margin. The lower postcanines, mostly worn out in the known specimens, are quadrangular until pc6 and then they are rectangular with the major axis anteroposteriorly oriented. They have a tall mesial border, possibly constituted by one labial and one lingual cusp, and a transverse ridge. After comparisons, the number of cusps in the sectorial, labial border of the upper gomphodont teeth, frequently used in phylogenetic analyses, would not necessary implies real homologies. For example, postcanine morphologies with one or more cusps anterior to the main labial cusp would not be homologous to morphologies with one or more cusps posterior to the main labial cusp, while resulting in a similar count of labial cusps.

Lamy Amphibian Quarry Taphonomy Redux and "Forensic Taphonomy"

The Lamy amphibian quarry is a famous quarry in the Garita Creek (=Tecovas) Formation of the Dockum Group in New Mexico. The quarry is well known for its large assemblage of metoposaurs, all presumably belonging to the taxon Koskinonodon perfectum (previously known as Buettneria perfecta). Anyone who has visited the Triassic portion of the Smithsonian Museum of Natural History in Washington, D.C. has probably seen the block of metoposaur skulls from this quarry on exhibit. It was originally interpreted to represent a group of metoposaurs dying in a small body of water dessicated by drought, but this new study proposes little evidence of this. Furthermore, the quarry was reopened and new blocks collected providing new information.

This paper also coins a new term "forensic taphonomy", which is the study of the taphonomy of a site solely utilizing field notes and previous publications without actually visiting the study area first hand. This type of work had been done previously for this site and while these authors defend this type of study in general, I'm left with the overall feeling that it is bad practice to discuss something as dependent on the proper interpretation of sedimentary structures and specimen orientations as taphomony without first hand observation of the site. Therefore, I'm glad they have revised their previous work by actually getting access to and reopening the quarry.

Finally, the authors briefly discuss an important caveat when studying specimens collected from bone-beds decades ago. To highlight what was thought to be key elements of the quarry, in this case the metoposaur skulls, the exhibitors had staff cover over many of the smaller bones around the skulls such as limb bones.  Thus "forensic taphonomy" interpretations based on this display block were skewed by the preparation and exhibit technique used.  This type of technique was also used to highlight two Coelophysis skeletons from the Late Triassic Coelophysis quarry, which are on exhibit at the American Museum of Natural History. "Undesirable" bones were removed or covered over, and tails were added to these specimens to make them complete.  Recent preparation techniques discourage the use of materials to mimic bone to make specimens appear complete, and also the past practice of amalgamating different specimens in bone panel mounts such as these.  Indeed, it can be extremely difficult to study older specimens prepared in this manner, as features of the specimens may not be real.  In fact some older, well known specimen descriptions actually describe the reconstruction, not the real bones. Be careful out there.

Lucas, S. G., Rinehart, L. F., Krainer, K., Spielmann, J. A., and A. B. Heckert. 2010. Taphonomy of the Lamy amphibian quarry: A Late Triassic bonebed in New Mexico, U.S.A. Palaeogeography, Palaeoclimatology, Palaeoecology 298:388398. doi:10.1016/j.palaeo.2010.10.025

Abstract - Located in Santa Fe County, New Mexico, USA, the Lamy amphibian quarry is a Late Triassic (Adamanian) bonebed stratigraphically low in the Garita Creek Formation of the Chinle Group. Well known for its mass accumulation of metoposaurid amphibians, it was initially interpreted as a drought-induced death assemblage. Based on microstratigraphic and sedimentological studies, additional and extensive collecting at the quarry and a revised understanding of the bonebed, we provide a detailed taphonomic analysis of the Lamy amphibian quarry that identifies it as a low diversity multitaxic and monodominant bonebed in pedogenically modified floodplain mudstone. The Lamy bonebed shows no evidence of drought and is characterized by a high density of completely dissociated bones that show clear alignment by current and sorting (enrichment of Voorhies Group II and III elements). The bones show no significant abrasion or weathering (stage 0), preserve virtually no evidence of scavenging and show no evidence of trampling. Based on skull lengths, the metoposaurid assemblage has a type I survivorship curve and lacks juveniles. We thus posit that the following sequence of events formed the Lamy amphibian bonebed: (1) aggregation (cause unknown) of a large number of metoposaurid amphibians at a site different from the location of the bonebed, though not distant; (2) catastrophic mass mortality; (3) complete disarticulation and disassociation of the skeletons; and (4) rapid transport of the disarticulated bones onto a floodplain surface that was undergoing pedogenesis. The Lamy amphibian bonebed is representative of the Late Triassic metoposaurid bonebeds from Morocco and the western USA, which are monodominant and nearly monotaxic. They indicate that aggregation (probably of breeding populations) and mass death of metoposaurids were relatively common across the riverine floodplains of Late Triassic Pangea.

Preserved Bark on Middle Triassic Gymnosperm Wood from Antarctica

Bark is rarely preserved in fossil trees so this is pretty significant.

Decombeix, A.-L., Taylor, E. L., and T. N. Taylor. 2010. Anatomy and affinities of permineralized gymnospermous trunks with preserved bark from the Middle Triassic of Antarctica. Review of Palaeobotany and Palynology 163:2634. doi:10.1016/j.revpalbo.2010.09.002

Abstract - Permineralized gymnosperm axes with pycnoxylic wood from the Middle Triassic Fremouw Formation of the Central Transantarctic Mountains, Antarctica, are assigned to the corystosperms (seed ferns) and conifers. Both groups have been previously described from this formation based on juvenile stems with attached leaf bases and decorticated trunks. Here we describe large axes with preserved bark from the Fremouw Peak permineralized peat locality. The specimens are characterized by a small parenchymatous pith with clusters of sclereids, a thick cylinder (> 10 cm) of pycnoxylic wood, and 1–2 cm of bark containing distinctive clusters of sclereids and a complex system of cortical vascular bundles. Comparison with axes previously described from the Middle Triassic of Antarctica shows that the new specimens are most similar to Kykloxylon, a corystosperm genus based on young stems bearing Dicroidium leaves, and with a portion of axis previously described as Rhexoxylon like. We suggest that both the new specimens and the Rhexoxylon-like axis represent proximal parts of a Dicroidium/Kykloxylon plant that possibly had a fluted trunk base, and we discuss the problem of delimiting features in corystosperm axes.

Embryonic Skeletal Morphology of the Jurassic Sauropodomorph Massospondylus

A few weeks ago I mentioned an upcoming article on sauropodomorph embryos from the Lower Jurassic of South Africa.  That article is now published in the Journal of Vertebrate Paleontology. This find represents the oldest occurrence of dinosaur embryonic material, but it also represents one of the oldest records of eggshell in the fossil record.  As far as I am aware (and someone please correct me if I am wrong) the only occurence of fossil eggs in the Triassic were associated with hatchlings of the sauropodomorph Mussaurus from the Upper Triassic El Tranquilo Formation of Argentina (Bonaparte and Vince, 1979). No calcified eggs are known from the Permian or earlier (Hirsch, 1979). Having worked in Cretaceous units where fossil eggshell is ubiquitous I'm always been curious about the lack of fossil eggshell in the Triassic. Years back I suggested that maybe fully calcified eggs hadn't developed yet, but was told by someone purportedly knowledgeable in fossil eggs that they were present, I just didn't know what look for.  I'm not really advocating my initial suggestion, but I'm not buying the latter explanation either.  Anyone else have any thoughts?

Reisz, R. R. , Evans, D. C. , Sues, H.-D. and D. Scott. 2010. Embryonic skeletal anatomy of the sauropodomorph dinosaur Massospondylus from the Lower Jurassic of South Africa. Journal of Vertebrate Paleontology 30:1653-1665. DOI:10.1080/02724634.2010.521604

Abstract - Two embryonic skeletons preserved inside thin-shelled eggs of a partially preserved clutch from the Upper Elliot Formation (Lower Jurassic) of South Africa have been attributed to the sauropodomorph dinosaur Massospondylus carinatus. A virtually complete skeleton is exposed in right lateral view, with the slightly telescoped skull and several cervical vertebrae extending beyond the eggshell. A second, partial skeleton has a skull preserved in dorsal view. The embryos have proportionately very large skulls, with the broad skull table formed by wide parietals and frontals. The wide posterolateral wing of the frontal separates the postorbital from contact with the parietal. The embryos have short rather than elongated cervical vertebrae, with tall rather than low neural arches. The large forelimbs are only slightly shorter than the hind limbs, which suggests an obligatory quadrupedal posture for the hatchlings. This pattern may represent an ontogenetic constraint related to the large size of the head and horizontally oriented neck. Similarities between the embryonic and post-hatchling specimens include the slenderness of the lower jaw and slight ventral curvature of the symphyseal portion of the dentary, the large supraorbital process of the prefrontal, and the tall antorbital and infratemporal fenestrae. There are 10 cervical, 14 dorsal, and three sacral vertebrae. The large distal claw-bearing phalanx of manual digit 1 is longer than any other phalangeal element of either manus or pes. The embryos of Massospondylus carinatus represent the oldest dinosaurian embryos known to date.

Unique Carapace Structure in a Triassic Tetrapod

Wow, and I thought that aetosaur carapaces were complex. Osteoderms provide more than defense and display.  They also provide support and stabilization for the axial skeleton. Choniosuchians seem to take this to a unique level.

Buchwitz, M. and S. Voigt. 2010. Peculiar carapace structure of a Triassic chroniosuchian implies evolutionary shift in trunk flexibility. Journal of Vertebrate Paleontology 30:1697-1708. DOI: 10.1080/02724634.2010.521685
Abstract - Dermal ossifications are widespread in Permian and Triassic tetrapods, but only members of the Chroniosuchia possess a series of dorsal osteoderms with a complex plate-to-plate articulation mechanism in addition to a contact between each osteoderm and its associated vertebral spine. The stratigraphically youngest chroniosuchid, Madygenerpeton pustulatus, from the Triassic of Kyrgyzstan provides new insight on the function of the chroniosuchian osteoderm system. Osteoderms of M. pustulatus are broad, peaked-roof-shaped to arched, with enlarged posterodorsal and anteroventral articulation facets bearing unique sets of concentric rail-like ridges and furrows. Supplementing the multiple-overlap chroniosuchian type articulation, the interlocking ridges and furrows confined the relative motion of two neighboring osteoderms to a rotation in slightly oblique and curved contact planes. Given the significant lateral narrowing of the dorsal ornamented non-overlap area, the horizontal component of the plate-to-plate rotation angles could reach up to 7.5◦, enabling more extensive lateral flexion of the trunk than in other chroniosuchids. Considering functional analogs, the chroniosuchian osteoderm system probably stabilized the vertebral column against shearing, torsion, tension, and compression loads and thus facilitated terrestrial locomotion at the expense of trunk flexibility. With its particular morphology, the carapace of M. pustulatus, however, was more suitable for locomotion styles featuring lateral body undulation than the carapaces of Permian chroniosuchids. We interpret this speciality as a secondary adaptation to an aquatic habitat.

Bentonyx sidensis, a new Rhynchosaur from the Middle Triassic of England

A note in the newest issue of the Journal of Vertebrate Paleontology reviews the type and referred material of the rhynchosaur Fodonyx spenceri and concludes that a referred skull actually belongs to a new taxon. This new taxon is named Bentonyx sidensis in honor of Professor Mike Benton of the University of Bristol, and authority on rhynchosaurs and a mentor to many students of the Triassic. You can read more about this is a recent post by David Hone, the third author on this paper.

I would like to congratulate Mike regarding this honor, especially in having the member of a taxon so dear to him named accordingly.

Langer, M. C. , Montefeltro, F. C. , Hone, D. E. , Whatley, R. and C. L. Schultz. 2010. On Fodonyx spenceri and a new rhynchosaur from the Middle Triassic of Devon. Journal of Vertebrate Paleontology 30:1884 — 1888.  DOI: 10.1080/02724634.2010.521901

Rainforest Collapse Triggered Carboniferous Tetrapod Diversification in Euramerica

A new paper that argues that ecosystem devestation in the Carboniferous provided conditions that led to increased diversity in amniotes and basically set the stage for the rise of archosaurs in the Mesozoic.

From Science Daily article: "Global warming devastated tropical rainforests 300 million years ago. Now scientists report the unexpected discovery that this event triggered an evolutionary burst among reptiles -- and inadvertently paved the way for the rise of dinosaurs, 100 million years later".  Read more here.

Sahney, S., Benton, M. J., and H. J. Falcon-Lang. 2010. Rainforest collapse triggered Carboniferous tetrapod diversification in Euramerica. Geology 38: 1079-1082. DOI: 10.1130/G31182.1

Abstract - Abrupt collapse of the tropical rainforest biome (Coal Forests) drove rapid diversification of Carboniferous tetrapods (amphibians and reptiles) in Euramerica. This finding is based on analysis of global and alpha diversity databases in a precise geologic context. From Visean to Moscovian time, both diversity measures steadily increased, but following rainforest collapse in earliest Kasimovian time (ca. 305 Ma), tetrapod extinction rate peaked, alpha diversity imploded, and endemism developed for the first time. Analysis of ecological diversity shows that rainforest collapse was also accompanied by acquisition of new feeding strategies (predators, herbivores), consistent with tetrapod adaptation to the effects of habitat fragmentation and resource restriction. Effects on amphibians were particularly devastating, while amniotes (‘reptiles’) fared better, being ecologically adapted to the drier conditions that followed. Our results demonstrate, for the first time, that Coal Forest fragmentation influenced profoundly the ecology and evolution of terrestrial fauna in tropical Euramerica, and illustrate the tight coupling that existed between vegetation, climate, and trophic webs.

"Triassic Attack"

Unfortunately (or maybe not) I missed this movie, which aired in the U.S. last Saturday, about a Native American curse that causes roadside dinosaur attractions to come alive and eat everything. Despite being called "Triassic Attack" the main culprits are reportedly a Tyrannosaurus and a Cretaceous age pterosaur. Based on the previews and other comments it was probably pretty enjoyably horrible as a B-movie should be, but I am dissapointed that the producers didn't educate themselves a bit and use actual Triassic critters.

Did anyone see this and care to report?

Stratigraphic Correlations of Gondwanan Basins in India and the "Laurasian" Fauna of Northern Gondwana in the Late Triassic

Here is a fairly obscure, but interesting new paper providing updated correlations of strata (including that of Triassic age) in the Gondwanan Basins of India. The final paper could have benefited from some more editing, but overall it provides a decent synthesis and outlines some of the problems of correlations in this are of Gondwana. Most significant is that there are no absolute time constraints available for these strata because of the lack of datable volcanic materials. The overall climate for the entire Triassic for this area is given as arid with a key sea level regression in the Norian. Note, however, that the authors explicitly use the 2004 ISC timescale, and that under currently proposed revisions to this timescale the Carnian is more restricted.

The Triassic vertebrate fauna of India has always struck me as bizarre, mainly because the Early Triassic fauna is extremely similar to that of the Lystrosaurus assemblage zone of South Africa, and does contain several species of Lystrosaurus. Yet the Middle and Late Triassic fauna has much more of a Laurasian feel to it, especially the Late Triassic fauna, which includes basal phytosaurs such as Parasuchus, and more advanced phytosaurs such as a Leptosuchus-like form. Aetosaurs are represented by a paratypothoracisine form, which are only known from North America and Europe. Finally, metoposaurid temnospondyls are also common as in North America and Europe.

This seems very odd to me given that in paleogeographic reconstructions throughout the Triassic, India is firmly nestled on the western edge of modern day Africa, contacting Australia, and Antarctica, and separated from North America by all of northern Africa and from Europe by the Tethys. Unfortunately the Triassic fauna of North Africa is extremely sparse, although the Moroccan fauna is very similar to that of India and Laurasia. Perhaps Northern Africa served as a corridor for the Laurasian-type fauna, whereas there was some restriction from South America and South Africa in the Latest Triassic.  Thus it seems that at this time there are not distinct Laurasian and Gondwanan distributions of tetrapods, but rather separate southern Gondwana and northern Gondwana/Laurasia distributions.

Mukhopadhyay, G., Mukhopadhyay, S. K., Roychowdhury, M., and P. K. Parui. 2010. Stratigraphic Correlation between Different Gondwana Basins of India.
Journal of the Geological Society of India 76:251-266. DOI: 10.1007/s12594-010-0097-6

Abstract - Gondwana Basins of India occur within the suture zones of Precambrian cratonic blocks of Peninsular India along some linear belts. More than 99% of the total coal resource of the country is present within these basins. The basins are demarcated by boundary faults having graben or half-graben geometry. These basins preserve a thick sedimentary pile deposited over nearly 200 million years from latest Carboniferous to Lower Cretaceous. However, due to lack of well-constrained data, age of most of the formations is assigned tentatively. This has resulted in diversified views on both intra- and inter-basinal stratigraphic correlation particularly in case of Upper Gondwana formations. It is well recognised that there are distinct spatial and temporal similarities in lithological, faunal and floral distribution in different Gondwana Basins of southern continents, including India, that were once part of supercontinent Gondwanaland. To address the problems of Indian Gondwana stratigraphy, during the present study, some unique events, also recognised in other parts of Gondwanaland, like marine flooding surfaces, large scale tectonic events or major change in depositional environment have been used as a tool for temporal correlation within the Gondwana Basins of India. Many of these events have been dated from different basins elsewhere. Considering these major events as time planes the total time span of deposition in Gondwana Basins has been classified into seven time slots. Recognition of these time planes helps in interbasinal correlation of different formations in Indian Gondwana basins and assigning the age, wherever available. This approach also helps in better understanding of basinal history. Unless otherwise mentioned, the time scale proposed by International Commission on Stratigraphy (2004) has been followed in this paper.

The First Detailed 3D visualizations of the Braincase and Vestibular System in a Permian Diapsid Reptile

Not Triassic but sill extremely significant for work on Triassic archosauromorphs as Youngina is often used as an outgroup for phylogenetic studies of this clade. Great new information, extremely cool, and of course open access!

Gardner, N. M., Holliday, C. M., anf F. R. O'Keefe. 2010. The braincase of Youngina capensis (Reptilia: Diapsida): new insights from high-resolution CT scanning of the holotype. Palaeontologia Electronica 13.3.19A.

Abstract - Detailed descriptions of braincase anatomy in early diapsid reptiles have been historically rare given the difficulty of accessing this deep portion of the skull, because of poor preservation of the fossils or the inability to remove the surrounding skull roof. Previous descriptions of the braincase of Youngina capensis, a derived stem-diapsid reptile from the Late Permian (250 MYA) of South Africa, have relied on only partially preserved fossils. High resolution X-ray computed tomography (HRXCT) scanning, a new advance in biomedical sciences, has allowed us to examine the reasonably complete braincase of the holotype specimen of Youngina capensis for the first time by digitally peering through the sandstone matrix that filled the skull postmortem. We present the first detailed 3D visualizations of the braincase and the vestibular system in a Permian diapsid reptile. This new anatomical description is of great comparative and phylogenetic relevance to the study of the structure, function and evolution of the reptilian head.

Nature News Article on Uatchitodon

I mentioned the new paper describing a new species of the purported venomous archosauriform Uatchitodon from the Chinle Formation and Newark Supergroup the other day.  Click this link to check out a new article in Nature News on this find and the paper's conclusions.

Free Access to the Journal Palaeobiodiversity and Palaeoenvironments in November 2010

For the month of November, Springer is offering open access to articles in the journal Palaeobiodiversity and Palaeoenvironments.  Recent artiles in this journal include the special issue on the "Triassic-Jurassic biodiversity, ecosystems, and climate in the Junggar Basin, Xinjiang, Northwest China".

Holy Lungfish! A Monster from the Cretaceous of North America

photo Kenshu Shimada
Wow! I missed this in the SVP abstract book this year.  Lungfish toothplates are a common fossil from the Chinle Formation, but I've never seen any specimen even come close to the size of this one from the Cretaceous of North America.  Unfortunately, the provenance is not exactly known; however, the specimen is 117mm wide and would have come from an animal with an estimated body length of 4 meters. That is one big dipnoan, a full two meters larger than living forms today. You can read more about this here. The suggested diet is turtles, but there are plenty of large freshwater invertebrates during the Cretaceous as well.

Morphological Diversity and Biogeography of Procolophonids

Cisneros, J. C., and M. Ruta. 2010. Morphological diversity and biogeography of procolophonids (Amniota: Parareptilia). Journal of Systematic Paleontology 8:607-625. DOI: 10.1080/14772019.2010.491986.

Abstract - A recent phylogenetic analysis of procolophonid parareptiles is used as the basis for a study of morphological diversity (disparity) in these amniotes. Disparity values are compared in three groups of procolophonids (a paraphyletic series of basal taxa and two monophyletic sister groups: procolophonines and leptopleuronines), two ecophenotypic assemblages (one based upon inferred diet - non high-fibre versus high-fibre species; the other based upon cranial sculpture - non horned versus horned species), and two temporal assemblages (Lower Triassic versus Middle and Upper Triassic). The mean disparity values are comparable in the case of temporal and ecophenotypic assemblages. High-fibre species are marginally less disparate than non high-fibre species. The combined Middle and Upper Triassic species are slightly less disparate than Lower Triassic species. Finally, horned species are only slightly more disparate than non-horned species. The paraphyletic series of basal taxa and the leptopleuronines show similar disparity values, marginally higher than those for procolophonines. Phylogenetic analysis is also used to reconstruct the biogeographical history of procolophonids. Both ancestral area analysis and dispersal-vicariance analysis show that South Africa was the most likely ancestral area for procolophonids as a whole. North China - either as a single area or in combination with Russia or South Africa - was the most likely ancestral area for the leptopleuronine-procolophonine clade.

New Species of the Late Triassic Venomous Archosauriform Uatchitodon

Mitchell, J. S., Heckert, A. B., and H.-D. Sues. 2010. Grooves to tubes: evolution of the venom delivery system in a Late Triassic “reptile”. Naturwissenschaften, online first. DOI 10.1007/s00114-010-0729-0

Abstract - Venom delivery systems occur in a wide range of extant and fossil vertebrates and are primarily based on oral adaptations. Teeth range from unmodified (Komodo dragons) to highly specialized fangs similar to hypodermic needles (protero- and solenoglyphous snakes). Developmental biologists have documented evidence for an infolding pathway of fang evolution, where the groove folds over to create the more derived condition. However, the oldest known members of venomous clades retain the same condition as their extant relatives, resulting in no fossil evidence for the transition. Based on a comparison of previously known specimens with newly discovered teeth from North Carolina, we describe a new species of the Late Triassic archosauriform Uatchitodon and provide detailed analyses that provide evidence for both venom conduction and document a complete structural series from shallow grooves to fully enclosed tubular canals. While known only from teeth, Uatchitodon is highly diagnostic in possessing compound serrations and for having two venom canals on each tooth in the dentition. Further, although not a snake, Uatchitodon sheds light on the evolutionary trajectory of venom delivery systems in amniotes and provide solid evidence for venom conduction in archosaur-line diapsids.

Supplemental data available here.

Madygenerpeton pustulatus, A New Chroniosuchid Reptilomorph from the Triassic of Kyrgyzstan

Schoch, R. R., Voigt, S., and M. Buchwitz. 2010. A chroniosuchid from the Triassic of Kyrgyzstan and analysis of chroniosuchian relationships. Zoological Journal of the Linnean Society 160: 515–530. doi:10.1111/j.1096-3642.2009.00613.x

Abstract - A nearly complete skull and associated osteoderms from the Middle/Upper Triassic Madygen Formation of Kyrgyzstan are referred to a new chroniosuchid genus and species. The new taxon is characterized by a parabolic skull outline, pustular ornamentation, tabular-squamosal contact, marked postparietal embayments, and the lack of an antorbital fontanelle. The palate is only preserved in part, showing broad palatines and ectopterygoids. Presence of a preorbital fenestra and characteristic osteoderm morphology are synapomorphies shared with all other chroniosuchids. According to the phylogenetic analysis performed, the new chroniosuchid nests with Chroniosaurus, with which it shares the wide, transversely extended osteoderms and pustular ornamentation. The chroniosuchians are robustly supported as a natural group, but their position within the reptiliomorph (stem-amniote) clade is not adequately understood. Whereas the parasphenoid is similar to that of anthracosaurs, most other characters support a higher nesting of chroniosuchians within the stem-amniotes.

Upcoming Article on Massospondylus (Sauropodomorpha) Embryos from the Lower Jurassic of Africa

A bunch of news articles have come out over the last two days discussing an upcoming article in the Journal of Vertebrate Paleontology discussing details of embrionic remains of the Jurassic sauropodomorph Massospondylus.

At this time it is unclear how this paper will differ from the original find of Massospondylus embryos in 2005.

You can check out two of the new stories (including photos) here and here.


Chinleana has Reached Over 100,000 Visitors

Today the counter at the bottom of the main page went over 100,000 hits. I'd like to thank everyone who has visited Chinleana over the last couple of years. When I decided to start a blog featuring mainly Triassic paleontology, I wondered if I would have enough material to make it a couple of months. Two years and three months later I have been able to post an average of every three days and there seems to be no shortage of news of material to post or discuss.  It absolutely amazes me how much Triassic related work is published each year and this is surely a tribute to the hard work of all of my Triassic colleagues and my readers. Thank you.

A New Paper That is Sure to Stir Up Some Debate

I'm not an expert on feathers so I can't offer an opinion but I'm sure lots of others will.

Dzik, J., Sulej, T., and G. Niedwiedzki. 2010. Possible link connecting reptilian scales with avian feathers from the early Late Jurassic of Kazakstan. Historical Biology 22: 394-402.

Abstract - Organic tissue of a recently found second specimen of feather-like Praeornis from the Karabastau Formation of the Great Karatau Range in southern Kazakstan, has a stable carbon isotope composition indicative of its animal affinity. Three-dimensional preservation of its robust carbonised shaft indicates original high contents of sclerotic organic matter, which makes the originally proposed interpretation of Praeornis as a keratinous integumental structure likely. The new specimen is similar to the holotype of Praeornis in the presence of three 'vanes' on a massive shaft not decreasing in width up to near its tip. Unlike it, the vanes are not subdivided into barbs and the pennate structure is expressed only in the distribution of organic-matter-rich rays. Similar continuous blades border the 'barbs' in the holotype, but the organic matter was removed from them by weathering. It is proposed that the three-vaned structure is a remnant of the ancestral location of scales along the dorsum and their original function in sexual display, similar to that proposed for the Late Triassic probable megalancosaurid Longisquama. Perhaps subsequent rotation around the shaft, in the course of evolution from an ancestral status similar to Praeornis towards the present aerodynamic and protective function of feathers, resulted in the tubular appearance of their buds.

Time Now for a Pseudosuchian - Desmatosuchus spurensis by Jeff Martz

Based on the traffic I've been getting everyone has really been enjoying the critter reconstructions by Jeff Martz. The past few days have focused on the ornithidirans but I think it is time to journey over to the other archosaurian branch.  Here is the aetosaur Desmatosuchus spurensis from the Late Triassic of the American southwest. If you really enjoy Jeff's work, please let him hear it.

Plateosaurus engelhardti Reconstruction by Jeffrey Martz

This is the last sample in Jeff Martz's dinosauromorph series and by far one of the most striking reconstructions, especially the coloration. This is the sauropodomorph Plateosaurus from the Upper Triassic of Germany.

Lesothosaurus diagnosticus Reconstruction by Jeff Martz

Here is a colorful, feathered, and very mean version of the Jurassic basal ornithischian Lesothosaurus from South Africa.  I think that this would make a great mascot for some college sports team.

Silesaurus opolensis Reconstruction by Jeff Martz

This is my favorite in Jeff's dinosauromorph series. The silesaurid dinosauriform Silesaurus from the Upper Triassic of Poland.

Marasuchus lilloensis Reconstruction by Jeffrey Martz

Continuing along on the new dinosauromorph series by Jeff Martz, here is a bluish version of the dinosauromorph Marasuchus from the Middle Triassic of Argentina.

Coelophysis bauri Reconstruction by Jeff Martz

A very colorful and fuzzy Coelophysis. Part of the new dinosauromorph series by Jeff Martz.

The neotheropod Coelophysis bauri from the Upper Triassic of New Mexico.

Herrerasaurus ischigualastensis Reconstruction by Jeff Martz

The herrerasaurid Herrerasaurus ischigualastensis from the Upper Triassic of Argentina

Tawa hallae Reconstruction by Jeff Martz

It has been awhile since I have featured some of Jeff Martz's Triassic critter artwork on this site.  Since that time his work has gained much more recognition, including some kudos from his mom!  He has posted some his more recent dinosauromorph material on his own site, but just in case you missed it I'll be reposting some of it here over the next few days.

The basal theropod Tawa hallae from the Upper Triassic Petrified Forest Member of the Chinle Formation in the Chama Basin of north-central New Mexico.

Chinle Formation Scenes

The Petrified Forest/Owl Rock Member contact in the Little Painted Desert north of Winslow, Arizona

Two New Papers on the Triassic/Jurassic Boundary

Kent, D. V., and E. Irving. 2010. Influence of inclination error in sedimentary rocks on the Triassic and Jurassic apparent pole wander path for North America and implications for Cordilleran tectonics. Journal Of Geophysical Research 115: B10103, doi:10.1029/2009JB007205

Abstract - Because of paleomagnetic inclination error (I error) in sedimentary rocks, we argue that previous estimates of Triassic and Jurassic paleolatitudes of the North American craton have generally been too low, the record being derived mostly from sedimentary rocks. Using results from all major cratons, we construct a new composite apparent pole wander (APW) path for Triassic through Paleogene based on 69 paleopoles ranging in age from 243 to 43 Ma. The poles are from igneous rocks and certain sedimentary formations corrected for I error brought into North American coordinates using plate tectonic reconstructions. Key features of the new APW path are a 25° northward progression from 230 to 190 Ma to high latitudes (off northernmost Siberia) where the pole lingers until 160 Ma, a jump to the Aleutians followed by a hook in western Alaska by ∼145 Ma that leads to the 130–60 Ma stillstand, after which the pole moves to its present position. As an example of the application of this new path we use paleomagnetic results to determine that southern Wrangellia and Stikinia (W/S), the two most westerly terranes in the Canadian Cordillera, lay 630 to 1650 km farther south than at present relative to the craton during the Late Triassic and Early Jurassic. This is consistent with an exotic Tethyan origin as paleontological and mantle geochemical evidences imply. During the Late Triassic through Early Cretaceous, W/S moved northward more slowly than the craton, implying oblique sinistral net convergence over this 130 Myr interval. This was followed by dextral shear in latest Cretaceous through Eocene.

Donohoo-Hurley, L. L., Geissman, J. W., and S. G. Lucas. 2010. Magnetostratigraphy of the uppermost Triassic and lowermost Jurassic Moenave Formation, western United States: Correlation with strata in the United Kingdom, Morocco, Turkey, Italy, and eastern United States. Geological Society of America Bulletin 122: 2005-2019; doi: 10.1130/B30136.1

Abstract - A composite magnetostratigraphy based on the magnetic polarity data from four sections of the uppermost Triassic and lowermost Jurassic Moenave Formation, Utah and Arizona, USA, can be correlated to the marine successions at Saint Audrie’s Bay (UK), Oyuklu, Turkey, and the Southern Alps, Italy, and to the nonmarine sections in Morocco, northern Africa, and the Newark Basin, eastern North America, all deposited across the Triassic–Jurassic boundary. Our proposed correlation provides a stratigraphic framework to tie Triassic–Jurassic sedimentation in the American Southwest to the marine UK, Turkey, and Italy sections, and to the Pangea rift history, including extrusive igneous rocks, preserved in Morocco and in the Newark Basin. The Moenave polarity record is characterized by mostly normal polarity, as is consistent with other polarity records across the Triassic–Jurassic boundary, and is interrupted by at least two well-defined reverse-polarity magnetozones. On the basis of available paleontologic information, we interpret the oldest well defined, reverse-polarity magnetozone, M2r of the Moenave Formation, to correlate with SA5n.2r or SA5n.3r of the Saint Audrie’s Bay record, H– of the Oyuklu record, BIT5n.1r of the Italcementi Quarry record, the oldest reverse magnetozone in sedimentary rocks in Morocco, and with reverse magnetozone E23r of the Newark Basin. The youngest reverse magnetozone of the Moenave Formation, M3r, is correlated to the latest Triassic magnetozones SA5n.5r of the Saint Audrie’s Bay record, J– of the Oyuklu record, and with the interval of reverse polarity in the “intermediate unit” of the Morocco record. Magnetostratigraphic correlations and marine biostratigraphic information support placement of the Triassic–Jurassic boundary in the middle to upper Whitmore Point Member of the Moenave Formation, the Lias Group of the Saint Audrie’s Bay section, the chert-rich limestone of the Oyuklu section, above the Zu Limestone in Italy, and in the central Atlantic magmatic province extrusive zone in the Morocco and the Newark records.

New Seed Ferns and Cycadophytes from the Middle Triassic of Germany

Kustatscher, E.,  and J. H. A. van Konijnenburg-van Cittert. 2010. Seed ferns and Cycadophytes from the Triassic Flora of Thale (Germany). Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen 258: 195–217.

Abstract: This is the second paper on the Middle Triassic flora from Thale, dealing with the seed ferns and cycadophytes. Scytophyllum bergeri Bornemann is one of the common elements in the flora, in contrast to Sagenopteris sp. which is rare in the assemblage. However, it is the first evidence of Sagenopteris for the German Basin. The specimen described as ?Peltaspermum sp. is the only peltasperm ovuliferous organ known to date with attached ovule-bearing discs from the Middle Triassic of Europe. The cycad Apoldia tener (Compter 1883) Zijlstra et al. 2009 (formerly Sphenozamites tener Compter) is by far the most common fossil plant in the assemblage. Nilssonia cf. neuberi Stur ex Pott et al. is relatively rare. The genus Bjuvia is emended to accommodate more species of large entire leaves characterised by amphistomy and cycadalean stomatal morphology. This includes Bjuvia thalensis n. sp., which is a common element in the Thale flora but is unknown from elsewhere. Narrow, long entire leaves from the Middle and Upper Triassic of Europe have been described under the name Taeniopteris angustifolia Schenk, but have now been transferred to Taeniopteris kelberi n. sp. for nomenclatorial reasons. The macrosporophyll Dioonitocarpidium pennaeformis (Schenk) Ruhle von Lilienstern also occurs in the Thale flora. Two cycadalean leaf species (Apoldia tener and Bjuvia thalensis) from Thale flora sometimes have stomata with only two subsidiary cells instead of the usual 4-6, a feature that in gymnosperms occurs mainly in the Bennettitales.

There are no Known Aetosaur Fossils from Madagascar!

I happened to click on the Wikipedia page for aetosaurs today. It is really shaping up as someone (or maybe a few people) is putting a lot of work into it. A few errors here and there and a couple taxonomic issues that will be addressed in some future publications (not all by me). However, the most glaring thing that caught my eye was location column for Desmatosuchus lists Madagascar (Isalo Group) as a unit containing fossils of Desmatosuchus. This is an occurrence I addressed in my M.S. thesis (Parker, 2003) and in my 2008 paper on the genus Desmatosuchus. It all stems from a problem in assigning a geological age to a fossil bearing horizon in the upper part of the Isalo II (part of the Isalo Group; Burmeister, 2000; Burmeister et al., 2006). This horizon includes fish fossils, as well as the remains of dinosaurs (sauropod, theropod) and other archosaurs, including teeth that are superficially similar to those of phytosaurs and a handful of osteoderms that belong to some type of pseudosuchian (see photo below from Burmeister, 2000).

Kurtis Burmeister first approached me in the late 1990s asking my opinion if these osteoderms could be from aetosaurs. I though the resemblance was purely superficial and despite he presence of an anterior bar and pitted ornamantation, the overall morphology and the lateral sutures were not typical of aetosaurs.  In his thesis, he suggested they could be crocodyliform (pers. comm. from Mike Parrish), but preliminarily assigned them to the Aetosauria and noted a possible assignment to Desmatosuchus. This identification was based on showing the osteoderms to another aetosaur "expert" (Burmeister, pers. comm.).

A few years later I was approached again by another member of the research team who showed me the specimens again.  This time I was with a small group of Triassic workers and coincidently we had a crocodyliform specialist with us as well.  We all agreed that they were definitely not Desmatosuchus, not aetosaurian, and most likely a crocodyliform. In a subsequent publication (Burmeister et al., 2006) they are refered to an indeterminate crocodylotarsian (pseudosuchian) and the superficial resemblance to aetosaurs is discussed, although the authors note the osteoderms probably represent a goniopholidid crocodyliform and that the horizon is probably Early Jurassic in age. Parker (2008) argued that they were not aetosaurian and possessed characters found in mesoeucrocodylians.

Despite all of this ambiguity, these specimens were explicitly assigned to the aetosaur Dematosuchus haplocerus by Lucas et al. (2003) and used to provide an Adamanian (late Carnian) age for these beds. This identification and correlation was followed by Lucas (2010).  Discussions with colleagues and the current Wikipedia entry for aetosaurs demonstrates that the identification of these specimens as aetosaurian is still misunderstood.  For the 4th time (and hopefully the last) I would like to propose my opinion (based on two personal observations of the material and the figure above) that these are not aetosaur plates and most certainly not referable to Desmatosuchus. The ornament is too deep and irregular, furhtermore, if these are fragments of paramedian plates then the ornament would be too large.  Finally, the sutural edges are completely different than anything found in aetosaurs, and certainly does not represent the "tongue-and-groove" articular surface found in desmatosuchines. There currently is no evidence for aetosaurs in the Isalo II and the age of the upper beds is most likely Jurassic (Burmeister et al., 2006; Parker, 2008) and not Adamanian in age (contra Lucas, 2010).


Burmeister, K.C., 2000, Paleogeographic and biostratigraphic implications of new early Mesozoic terrestrial vertebrate fossils from the Poamay site: central Morondava Basin, Madagascar [M.A. thesis]: Santa Barbara, University of California, 109 p.

Burmeister, K.C., J.J. Flynn, J.M. Parrish, and A.R. Wyss. 2006. Paleogeographic and biostratigraphic implications of new early Mesozoic vertebrates from Poamay, central Morondava Basin, Madagascar. New Mexico Museum of Natural History Science Bulletin 37:457–475.

Lucas, S.G. 2010. The Triassic timescale based on nonmarine tetrapod biostratigraphy and biochronology; pp. 447-500 in  Lucas, S. G. (ed.) The Triassic Timescale. Geological Society, London, Special Publications, 334.

Lucas, S.G., K.E. Zeigler, A.B. Heckert, and A.P. Hunt. 2003. Upper Triassic stratigraphy and biostratigraphy, Chama Basin, north-central New Mexico. New Mexico Museum of Natural History & Science Bulletin 24:15–39.

Parker, W.G. 2003. Description of a new specimen of Desmatosuchus haplocerus from the Late Triassic of Northern Arizona. M.S. thesis. Northern Arizona University, Flagstaff, AZ.

Parker, W.G. 2008. Description of new material of the aetosaur Desmatosuchus spurensis (Archosauria: Suchia) from the Chinle Formation of Arizona and a revision of the genus Desmatosuchus. PaleoBios 28:1-40. 

Sterling Nesbitt Online!

My very good friend and colleague Sterling Nesbitt has a new website detailing his work (mainly on Triassic archosauromorphs). Please go check it out and then totally harass him for PDFs of all of his papers.

Much of the renniassance in Triassic archosauromorph taxonomy and phylogeny is in a large part due to Sterling's work over the last decade. His forthcoming, in press, absolutely monstrous (over 500 manuscript pages) monograph on archosauromorph phylogeny (from his doctoral dissertation) promises to be the most comprehensive work ever done on this group (over 50 taxa and 400 characters, almost all scored through first hand observation of the actual specimens) and will be a foundation study for years to come.

The Future Direction of Late Triassic Terrestrial Ecosystem Research

Here is an excellent synthesis by Randall Irmis and Jessica Whiteside of ongoing and future research in the Late Triassic, particularly in North America. These are topics of great interest to me and Jeff Martz right now and we have a paper in press that will delve into our side of this research.  We are also working closely with colleagues such as Randy and Jessica on some aspects of this work and I am proud that Petrified Forest National Park is one of the settings for this exciting research.

It is a Spotlight article so there is no abstract. You can e-mail Randall Irmis for a PDF.

This excerpt makes a key point that I have been a strong proponent for:

"The key for understanding Late Triassic terrestrial ecosystems is that all of these new studies focus on stratigraphic sections where multiple different research approaches can be applied to maximize the data recovered from the same area."

Instead  of various researchers working haphazardly, conducting different studies on different outcrops, coordinating this research instead with everyone working in the same areas under the same detailed stratigraphic foundation allows for a final amalgamation of data leading to stronger supported interpretations for all parties involved. This is exactly what has been going on at the Petrified Forest over the last few years and the story coming out of the rocks and fossils is just amazing.

Irmis, R. B., and J. H. Whiteside. 2010. Newly integrated approaches to studying Late Triassic terrestrial ecosystems. Palaios 25:689-691. DOI: 10.2110/palo.2010.S06

Sanjuansaurus gordilloi a new Herrerasaurid from Argentina

Here is a new herrerasaurid from the the Ischigualasto Formation of Argentina. Looks much more similar to Herrerasaurus than to Staurikosaurus or Chindesaurus, although the latter taxon was not included in the phylogenetic analysis.  This analysis finds Herrerasauridae to be the sister taxon to Eoraptor + (Guaibasaurus + Neotheropoda), so we are back to the position of herrerasaurids still being dinosaurs but as basal saurischians rather than theropods.  Comparison is provided in the text to Tawa hallae, but it is not included in the phylogenetic analysis.  Too bad.  However, I'm pretty certain that based on the current material coding Sanjuansaurus into the analysis of Nesbitt et al. (2009) would not change the position of herrerasaurids as basal theropods as recovered in that analysis. So whether or not herrerasaurids are theropods or not appears to be entirely dependent on the base matrix one uses. Thus, unfortunately, the analysis in this paper does not appear to offer anything particularly game-changing or significant in that regards. Also unfortunate is that there is no discussion of these differing hypotheses in the paper.

The further recognition of the increased diversity of basal saurischian dinosaurs in the latest Carnian is interesting and provides more circumstantial support for the earlier diversification of Archosauria in the Early Triassic as hypothesized by Nesbitt (2009) based on body fossils and more recently by Brusatte et al. (2010) based on footprint evidence. 

Alcober O.A., and R. N. Martinez. 2010. A new herrerasaurid (Dinosauria, Saurischia) from the Upper Triassic Ischigualasto Formation of northwestern Argentina. ZooKeys 63 : 55 – 81 . doi: 10.3897/zookeys.63.550

Abstract - Herrerasauridae comprises a basal clade of dinosaurs best known from the Upper Triassic of Argentina and Brazil, which have yielded remains of Herrerasaurus ischigualastensis and Staurikosaurus pricei, respectively. Systematic opinion regarding the position of Herrerasauridae at the base of Dinosauria has varied. Here we describe a new herrerasaurid, Sanjuansaurus gordilloi gen. n., sp. n., based on a partial skeleton from Carnian-age strata of the the Upper Triassic Ischigualasto Formation of northwestern Argentina. The new taxon is diagnosed by numerous features, including long, band-shaped and posterolaterally oriented transverse process on the posterior cervical vertebrae; neural spines of the sixth to eighth dorsal vertebrae, at least, bearing acute anterior and posterior processes; scapula and coracoid with everted lateral margins of the glenoid; and short pubis (63% of the femoral length). Phylogenetic analysis placed Sanjuansaurus within a monophyletic Herrerasauridae, at the base of Theropoda and including Herrerasaurus and Staurikosaurus. The presence of Sanjuansaurus at the base of the Ischigualasto Formation, along with other dinosaurs such as Herrerasaurus, Eoraptor, Panphagia, and Chromogisaurus suggests that saurischian dinosaurs in southwestern Pangea were already widely diversified by the late Carnian rather than increasing in diversity across the Carnian-Norian boundary.

Holotype specimen of Sanjuansaurus gordilloi (PVSJ 605)
Brusatte, S. L., Niedźwiedzki, G., and R. J. Butler. 2010. Footprints pull origin and diversification of dinosaur stem lineage deep into Early Triassic. Proceedings of the Royal Society B. doi: 10.1098/rspb.2010.1746

Nesbitt, S. J. 2009. The antiquity of Archosauria and the origin of Late Triassic archosaur assemblages. Journal of Vertebrate Paleontology 29:155A.

Nesbitt, S. J., Smith, N. D., Irmis, R. B.,Turner, A. H., Downs, A., and M. A. Norell. 2009. A Complete skeleton of a Late Triassic saurischian and the early evolution of dinosaurs. Science 326: 1530–1533.