Field of Science

Revisiting the Cranial Anatomy of the Thalattosaur Anshunsaurus huangnihensis

Cheng, L., Chen, X., Zhang, B., and Y. Cai. 2011. New Study of Anshunsaurus huangnihensis Cheng, 2007 (Reptilia: Thalattosauria): Revealing its Transitional Position in Askeptosauridae. Acta Geologica Sinica (English Edition) 85: 1231–1237. doi: 10.1111/j.1755-6724.2011.00584.x

Abstract - The skull of Anshunsaurus huangnihensis Cheng, 2007, especially the skull roof, is described in detail in this paper. Compared to other genera and species of Askeptosauroidea, Anshunsaurus huangnihensis has some important transitional characters from Askeptosaurus italicus to Anshunsaurus huangguoshuensis: the rostral length related to the skull length between Askeptosaurus italicus and Anshunsaurus huangguoshuensis; the postfrontal existing but distinctly reduced; the posterolateral process relatedly short and overlapping the parietal. The phylogenetic analysis weakly supports the evolutional progress from Anshunsaurus huangnihensis to Anshunsaurus huangguoshuensis. The skeletal ratios indicated that the node among the Askeptosauridae ingroup. The evolutional direction of Askeptosauridae should be from Askeptosaurus italicus to Anshunsaurus huangguoshuensis. The skeletal ratios indicated that the evolutional progress is Askeptosaurus italicus -- Anshunsaurus huangnihensis -- Anshunsaurus huangguoshuensis. In biogeography provinces, the Askeptosauroidea taxa from south China have a close relationship with those from western Tethys; however, Xinpusaurus from the Late Triassic is more related to those from the eastern Pacific.

New Open Access Paper Publishing Field Notes from the 1932 Excavations at Trossingen, Germany


Schoch, R. R. 2011. Tracing Seemann’s dinosaur excavation in the Upper Triassic of Trossingen: his field notes and the present status of the material. Palaeodiversity 4: 245–282.

Abstract - The field notes of Reinhold Seemann, who conducted the 1932 dinosaur excavation at Trossingen, are published for the first time. An English translation of the whole text is also provided. Quarry maps and stratigraphic sections were redrawn and compared with new data gathered in ongoing excavations. Of the 65 finds listed by Seemann, only 21 have survived the Second World War (Plateosaurus: 18, Proganochelys: 3). This includes most of the well-preserved skeletons, which had been moved to safe places during the war. An overview of these finds and their present state is given for the first time. This reveals major differences in preservation of bones, and it adds to the knowledge of bone completeness classes at Trossingen. The missing finds were probably destroyed by fire in 1944, and there are no remains from these specimens left. In combination with the field notes and sketches, the new data on Seemann’s material may serve as a platform for future studies of and excavations at the Trossingen lagerstaette.

There Goes "Dicynodon" Biostratigraphy!

In the latest Journal of Vertebrate Paleontology Memoir Christian Kammerer, Kenneth Angielczyk, and Jörg Fröbisch (an allstar team of synapsid workers) readily handle the taxonomic mess more commonly known as Dicynodon. They find that the taxon is polyphyletic, is restricted to two species, and reassign all of the other material to a variety of old and new genera. Moreover, I think that their abstract sets a record for the number of included taxonomic names. 

Hey guys, want to tackle "Rutiodon" next?

Kammerer, C. F., Angielczyk, K. D., and J. Fröbisch. 2011. A comprehensive taxonomic revision of Dicynodon (Therapsida, Anomodontia) and its implications for dicynodont phylogeny, biogeography, and biostratigraphy. Journal of Vertebrate Paleontology 31, Supplement 1: 1-158 DOI:10.1080/02724634.2011.627074

Abstract - The dicynodont wastebasket genus Dicynodon is revised following a comprehensive review of nominal species. Most nominal species of Dicynodon pertain to other well-known dicynodont genera, especially Oudenodon and Diictodon. Of the Karoo Permian species that are referable to "Dicynodon" sensu lato, we recognize four common, valid morphospecies: Dicynodon lacerticeps, D. leoniceps, D. woodwardi, and Dinanomodon gilli, comb. nov. Eleven additional species of "Dicynodon" are recognized worldwide: D. alticeps, D. amalitzkii, D. bathyrhynchus, D. benjamini, D. bogdaensis, D. huenei, D. limbus, D. sinkianensis, D. traquairi, D. trautscholdi, and D. vanhoepeni. Morphometric analysis of D. lacerticeps and D. leoniceps specimens recovers statistically significant separation between these species in snout profile and squamosal shape, supporting their distinction. A new phylogenetic analysis of Anomodontia reveals that "Dicynodon" is polyphyletic, necessitating taxonomic revision at the generic level. D. benjamini and D. limbus are basal cryptodonts, whereas the other valid "Dicynodon" species are basal dicynodontoids. The genus Dicynodon is restricted to D. lacerticeps and D. huenei. We reinstate use of Daptocephalus, Sintocephalus, Turfanodon, Daqingshanodon, Jimusaria, and Gordonia for other species. We synonymize Vivaxosaurus permirus and Dicynodon trautscholdi (as V. trautscholdi, comb. nov.) We establish new generic names for several species formerly included in Dicynodon: Peramodon amalitzkii, comb. nov., Keyseria benjamini, comb. nov., Euptychognathus bathyrhynchus, comb. nov., Syops vanhoepeni, comb. nov., and Basilodon woodwardi, comb. nov. Of the main Karoo Permian taxa, Dicynodon, Basilodon, and Dinanomodon range throughout the Cistecephalus and Dicynodon assemblage zones, but Daptocephalus is restricted to the Dicynodon Assemblage Zone.

Hitchcock's Birds

Brian Switek has a wonderful post on the dinosaur trackways of New England over at the Dinosaur Tracking Blog.  I grew up in Connecticut and as a boy enjoyed going to Dinosaur State Park to see the trackways.  My first foray into the Triassic.

David Peter's Take on Revueltosaurus

David Peters has a new post up on his blog that has been getting some attention including on Facebook.  I'll address it shortly but first I'd like to apologize for the long delay in getting the full description of this taxon out in publication, especially since everyone has now seen Jeff Martz's amazing reconstruction. Originally I suggested he submit it for the Lanzandorf prize because I thought the paper would actually be submitted by that point. The main text has been near completion for some time now and very recently revised.  The hang-up is in completing the figures and because I keep taking on other tasks and responsibilities keeping me from focusing on the project. 

David Peters post with the suggestion that Revueltosaurus may be a paracrocodylomorph is actually fairly insightful given that he has not seen the material first hand and is relying solely on preliminary descriptions and Jeff's reconstruction.  Revueltosaurus is an amazing critter because it possesses character states found in a variety of suchian taxa, including paracrocodylomorphs; however, it has many characters only shared with aetosaurs which results in the position found by Nesbitt (2011). Sterling's coding was based on a thorough examination of all presently known material and although I don't agree with 100% of his codings I don't think the phylogenetic position of Revueltosaurus will change with the publication of the full description and revised phylogenetic analysis.

I'd ask everyone to please be a bit more patient and we'll get the paper out. I realize that it is an important taxon and as a result a lot of people want/need to see the material.

Aetosaurs Made Brachychirotherium Footprints

Lucas, S. G., and A. B. Heckert. 2011. Late Triassic aetosaurs as the trackmaker of the tetrapod footprint ichnotaxon Brachychirotherium. Ichnos 8: 197-208 DOI:10.1080/10420940.2011.632456

Abstract - Brachychirotherium is the common ichnogenus of Late Triassic chirothere footprints well known from western Europe, North America, Argentina and South Africa. Although it has long been agreed by most workers that the trackmaker of Brachychirotherium was a derived crurotarsan archosaur, the trackmaker has been identified as either a rauisuchian or an aetosaur, and some workers attribute it to a primitive crocodylomorph (sphenosuchian). New knowledge of the osteology of the manus and pes of a large aetosaur, Typothorax coccinarum, indicates a close correspondence between the manus and pes structure of aetosaurs and the morphology of Brachychirotherium. Furthermore, functional analysis of complete skeletons indicates aetosaurs plausibly placed their feet in the narrow gauge, nearly the overstepped walk characteristic of Brachychirotherium. Brachychirotherium and aetosaurs have matched distributions, that is, they were Pangea-wide during the Late Triassic. The manus and pes morphology of rauisuchians and early crocodylomorphs (sphenosuchians) deviate from Brachychirotherium footprint morphology in key features, thus excluding their identification as trackmakers. Aetosaurs made Brachychirotherium footprints.

Archaeologists vs. Paleontologists

The following blurb is from http://uncyclopedia.wikia.com/wiki/Archaeologist#Archaeologists_VS_Paleontologists
The rivalry between archaeologists and paleontologists has been around ever since Hanna Barbara leaked top secret documentary footage showing that humans, dinosaurs, and Pleistocene mega fauna coexisted. This has led to a sibling rivalry, in which neither party can safely work beside the other, for fear of Indian burns, and getting told on to mom and dad. This forces each party to work in complete isolation from each other.
Archaeologists, for their part, hate paleontologists, because nobody in the general public knows what archaeology is, and the general public mistakenly assumes that they are looking for fossils of extinct animals. Paleontologists hate archaeologists for similar reasons, because the general public always asks them if they are archaeologists, and assumes they are looking for buried treasures, such as artifacts, coins, and arrowheads, and constantly asks archaeologists if they are paleontologists.
Public, Please get it right; Archaeologists look for people. Paleontologists look for animals.
I think almost all of us in the paleo profession have encountered this at one time or another explaining what we do to old friends, family, and the public. I've found when I try to correct them I'm just met with blank stares, especially if I try to go beyond the term "dinosaur" at all, so I usually don't bother anymore. It always amazes me that the public is certainly familiar with both terms but consistently gets them backwards when it come to the objects of interest. I've also heard what the first sentence of the article is hinting at, that most people's (Americans at least) only interaction with paleontology is through the Flintstones TV show.  Moreover I also have a hunch that this confusion may be why there are so few paleontologists employed by the U.S. government compared to thousands of archaeologists. A colleague blames the Cope vs. Marsh bone wars for souring the government on paleontology, but I think they might just be confused about the terms and historically thought they actually had it all covered. After all isn't that what archaeologists study?

Kyrgyzsaurus, a new Drepanosaur from the Triassic Madygen Formation of Kyrgyzstan

Alifanov, V. R., and E. N. Kurochkin. 2011. Kyrgyzsaurus bukhanchenkoi gen. et sp. nov., a new reptile from the Triassic of southwestern Kyrgyzstan. Paleontological Journal 45(6): 639-647 DOI: 10.1134/S0031030111060025

Abstract - A new reptile, Kyrgyzsaurus bukhanchenkoi gen. et sp. nov., from the Triassic (Madygen Formation) of southwestern Kyrgyzstan is described based on the anterior part of the skeleton (skull, cervical and anterior dorsal vertebrae, ribs, pectoral girdle) and skin imprints. This is the most archaic representative of the family Drepanosauridae (Archosauromorpha, Diapsida). The most prominent features of the new form are the shortened lower jaw, numerous teeth, granular body osteoderms, large supraorbital shelflike skin folds, and thick and extensive throat sac.

New Paper on Permo-triassic Therapsids from Eastern Europe

M. F. Ivakhnenko, M. F. 2011. Permian and Triassic Therocephals (Eutherapsida) of Eastern Europe. Paleontological Journal 45: 981-1144 DOI: 10.1134/S0031030111090012

Abstract - Cranial morphology of Permian and Triassic Therocephalia of Eastern Europe is revised. The Therocephalia are regarded as an order of the subclass Eutherapsida of the class Theromorpha. Phylogenetic relationships are reconsidered and a tentative taxonomic scheme of the order is proposed. Biomorph evolution of East European Therocephalia from the Middle Permian to the Middle Triassic are discussed.

Aesop's Fable - The Triassic version - the Dinosaur and the Crocodile

You can read it here:

http://www.economist.com/node/21540979

Triassic palaeontology in the Economist.

Braincase of the Temnospondyl Gerrothorax from the Middle Triassic of Germany

Witzmann, F., Schoch, R. R., Hilger, A. and N. Kardjilov. 2011. Braincase, palatoquadrate and ear region of the plagiosaurid Gerrothorax pulcherrimus from the Middle Triassic of Germany. Palaeontology (early online). doi: 10.1111/j.1475-4983.2011.01116.x

Abstract - The complete neurocranium plus palatoquadrate of the plagiosaurid temnospondyl Gerrothorax pulcherrimus from the Middle Triassic of Germany is described for the first time, based on outer morphological observations and micro-CT scanning. The exoccipitals are strong elements with paroccipital processes and well-separated occipital condyles. Anterolaterally, the exoccipitals contact the otics, which are mediolaterally elongated and have massive lateral walls. The otics contact the basisphenoid, which shows well-developed sellar processes. Anteriorly, the basisphenoid is continuous with the sphenethmoid region. In its posterior portion, the sphenethmoid gives rise to robust, laterally directed laterosphenoid walls, a unique morphology among basal tetrapods. The palatoquadrate is extensively ossified. The quadrate portion overlaps the descending lamina of squamosal and ascending lamina of pterygoid anteriorly, almost contacting the epipterygoid laterally. The epipterygoid is a complex element and may be co-ossified with otics and laterosphenoid walls. It has a broad, sheet-like footplate and a horizontally aligned ascending process that contacts the laterosphenoid walls. The degree of ossification of the epipterygoid, however, is subject to individual variation obviously independent from ontogenetic changes. The stapes of Gerrothorax is a large, blade-like element that differs conspicuously from the plesiomorphic temnospondyl condition. It has a prominent anterolateral projection which has not been observed in other basal tetrapods. Morphology of neurocranium and palatoquadratum of Gerrothorax most closely resembles that of the Russian plagiosaurid Plagiosternum danilovi, although the elements are less ossified in the latter. The extensive endocranial ossification of Gerrothorax is consistent with the general high degree of ossification in the exo- and endoskeleton of this temnospondyl and supports the view that a strong endocranial ossification cannot be evaluated as a plesiomorphic character in basal tetrapods.

Disparity and Convergence in Bipedal Archosaur Locomotion

Bates, K. T., and E. R. Schachner. 2011. Disparity and convergence in bipedal archosaur locomotion. Journal of the Royal Society Interface (advance online publication) doi: 10.1098/​rsif.2011.0687

Abstract - This study aims to investigate functional disparity in the locomotor apparatus of bipedal archosaurs. We use reconstructions of hindlimb myology of extant and extinct archosaurs to generate musculoskeletal biomechanical models to test hypothesized convergence between bipedal crocodile-line archosaurs and dinosaurs. Quantitative comparison of muscle leverage supports the inference that bipedal crocodile-line archosaurs and non-avian theropods had highly convergent hindlimb myology, suggesting similar muscular mechanics and neuromuscular control of locomotion. While these groups independently evolved similar musculoskeletal solutions to the challenges of parasagittally erect bipedalism, differences also clearly exist, particularly the distinct hip and crurotarsal ankle morphology characteristic of many pseudosuchian archosaurs. Furthermore, comparative analyses of muscle design in extant archosaurs reveal that muscular parameters such as size and architecture are more highly adapted or optimized for habitual locomotion than moment arms. The importance of these aspects of muscle design, which are not directly retrievable from fossils, warns against over-extrapolating the functional significance of anatomical convergences. Nevertheless, links identified between posture, muscle moments and neural control in archosaur locomotion suggest that functional interpretations of osteological changes in limb anatomy traditionally linked to postural evolution in Late Triassic archosaurs could be constrained through musculoskeletal modelling.

New Material of the Cynodont Dadadon isaloi from the Triassic of Madagascar

Ranivoharimanana, L., Kammerer, C. F., John J. Flynn, J. J., and A. R. Wyss. 2011. New material of

Abstract - New material of the traversodontid cynodont Dadadon isaloi from the Triassic of southwestern Madagascar is described. The new material consists of a complete, well-preserved skull (FMNH PR 2232) and an unassociated, partial lower jaw (UA 10608). The new material reveals several novel aspects of Dadadon's morphology. Newly recognized autapomorphies that diagnose Dadadon include a fourth upper incisor with posterior accessory cusp, deep interorbital depressions confined to the frontals, and a very tall, robust mid-frontal ridge. Dadadon can further be distinguished from the similar traversodontids Massetognathus and Santacruzodon by the presence of shorter, broader prefrontals with prominent dorsal depressions, robust anterolateral processes overhanging the orbits, a single cusp in the anterior cingulum of the upper postcanines, and relatively elongate, striated, conical upper incisors. In a revised phylogenetic analysis incorporating data from the new specimens, Dadadon is recovered in a clade with Massetognathus and Santacruzodon. This clade is the sister taxon to the well-supported traversodontid subclade Gomphodontosuchinae. The ‘basal Isalo II’ cynodont fauna from Madagascar is more similar in composition to that of South America than to mainland Africa, although this is probably attributable to the lack of Ladinian–Carnian therapsid fossils on the mainland rather than an actual biogeographic pattern.
Dadadon isaloi (Cynodontia, Traversodontidae) from the Triassic of Madagascar. Journal of Vertebrate Paleontology 31:1292-1302. DOI:10.1080/02724634.2011.618154

Osteohistology of Some Triassic Archosauromorphs

Botha-Brink, J., and R. M. H. Smith. 2011. Osteohistology of the Triassic archosauromorphs Prolacerta, Proterosuchus, Euparkeria, and Erythrosuchus from the Karoo Basin of South Africa. Journal of Vertebrate Paleontology 31:1238-1254. DOI:10.1080/02724634.2011.621797

Abstract - The South African non-archosauriform archosauromorph Prolacerta and the archosauriforms Proterosuchus, Erythrosuchus, and Euparkeria were important constituents of the Early to early Middle Triassic Karoo ecosystem following the end-Permian mass extinction. We present new data on the osteohistology of these stem archosaurs and provide insight into their paleobiology. Bone tissues of the Early Triassic Prolacerta contain a poorly defined fibro-lamellar complex, with parallel-fibered bone in some regions, whereas the contemporaneous Proterosuchus exhibits rapidly forming uninterrupted fibro-lamellar bone early in its ontogeny, which becomes slow forming lamellar-zonal bone with increasing age. The early Middle Triassic Erythrosuchus deposited highly vascularized, uninterrupted fibro-lamellar bone throughout ontogeny, whereas the growth of the contemporaneous Euparkeria was relatively slow and cyclical. When our data are combined with those of previous studies, preliminary results reveal that Early and Middle Triassic non-crown group archosauromorphs generally exhibit faster growth rates than many of those of the Late Triassic. Early rapid growth and rapid attainment of sexual maturity are consistent with life history expectations for taxa living in the unpredictable conditions following the end-Permian mass extinction. Further research with larger sample sizes will be required to determine the nature of the environmental pressures on these basal archosaurs.

Redescription of a Nearly Complete Skull of Plateosaurus from the Late Triassic of Germany

Prieto-Márquez, A., and M. A. Norell. 2011. Redescription of a nearly complete skull of Plateosaurus (Dinosauria: Sauropodomorpha) from the Late Triassic of Trossingen (Germany). American Museum Novitates 3727 :1-58. 
doi:
http://www.bioone.org/doi/abs/10.1206/3727.2

Abstract - The nearly complete, disarticulated skull of AMNH FARB 6810, a specimen of the basal sauropodomorph Plateosaurus collected in 1925 from the Norian (Late Triassic) strata of the Knollenmergel beds of Trossingen (Germany), is redescribed. This study supports referral of AMNH FARB 6810 to P. erlenbergiensis on the basis of the following characters: occipital condyle above level of parasphenoid; basisphenoid with transverse, subvertical lamina extending between basipterygoid processes, with ventrally projecting median process; and peglike process projecting medially from the middle of the palatine. Furthermore, P. longiceps is regarded a junior synonym of P. erlenbergiensis because the type specimen of the latter is diagnostic (displaying the above-noted apomorphies of the braincase and palatine) and, chronologically, P. erlenbergiensis has priority over P. longiceps.

Did An Extraterrestrial Impact Hasten the End-Triassic Extinction On Land?

This is a interesting news article in Nature examining work by Drs. Paul Olsen and Dennis Kent on the possibility that the Rochechouart impact in France may have had an adverse effect on global terrestrial populations around 200 million years ago. The article also includes an excellent new Triassic scene by Victor O. Leshyk, which features Redondavenator and Redondasaurus from the Upper Triassic Redonda Formation of New Mexico. There is also a Typothorax-like aetosaur in the background for armodillodile fans.

Pampadromaeus barberenai, a New Basal Sauropodomorph from the Late Triassic of Brazil

For those of you who were at SVP this year, this is the new dinosaur taxon from the Triassic of Brazil that Max Langer presented on.

Cabreira, S. F., Schultz, C. L., Bittencourt, J. S., Soares, M. B., Fortier, D. C., Silva, L. R., and M. C. Langer. 2011. New stem-sauropodomorph (Dinosauria, Saurischia) from the Triassic of Brazil. Naturwissenschaften (advance online publication) DOI: 10.1007/s00114-011-0858-0

Abstract - Post-Triassic theropod, sauropodomorph, and ornithischian dinosaurs are readily recognized based on the set of traits that typically characterize each of these groups. On the contrary, most of the early members of those lineages lack such specializations, but share a range of generalized traits also seen in more basal dinosauromorphs. Here, we report on a new Late Triassic dinosaur from the Santa Maria Formation of Rio Grande do Sul, southern Brazil. The specimen comprises the disarticulated partial skeleton of a single individual, including most of the skull bones. Based on four phylogenetic analyses, the new dinosaur fits consistently on the sauropodomorph stem, but lacks several typical features of sauropodomorphs, showing dinosaur plesiomorphies together with some neotheropod traits. This is not an exception among basal dinosaurs, the early radiation of which is characterized by a mosaic pattern of character acquisition, resulting in the uncertain phylogenetic placement of various early members of the group.

Leyesaurus marayensis, a New Basal Sauropodomorph from Argentina and a Reanalysis of the Paleobiogeography of the Massospondylids

Apaldetti, C., Martinez, R. N., Alcober, O. A., and D. Pol. 2011. A New Basal Sauropodomorph (Dinosauria: Saurischia) from Quebrada del Barro Formation (Marayes-El Carrizal Basin), Northwestern Argentina.PLoS ONE 6(11): e26964. doi:10.1371/journal.pone.0026964

BackgroundArgentinean basal sauropodomorphs are known by several specimens from different basins; Ischigualasto, El Tranquilo, and Mogna. The Argentinean record is diverse and includes some of the most primitive known sauropodomorphs such as Panphagia and Chromogisaurus, as well as more derived forms, including several massospondylids. Until now, the Massospondylidae were the group of basal sauropodomorphs most widely spread around Pangea with a record in almost all continents, mostly from the southern hemisphere, including the only record from Antarctica.

Methodology/Principal FindingsWe describe here a new basal sauropodomorph, Leyesaurus marayensis gen. et sp. nov., from the Quebrada del Barro Formation, an Upper Triassic-Lower Jurassic unit that crops out in northwestern Argentina. The new taxon is represented by a partial articulated skeleton that includes the skull, vertebral column, scapular and pelvic girdles, and hindlimb. Leyesaurus is diagnosed by a set of unique features, such as a sharply acute angle (50 degrees) formed by the ascending process of the maxilla and the alveolar
margin, a straight ascending process of the maxilla with a longitudinal ridge on its lateral surface, noticeably bulging labial side of the maxillary teeth, greatly elongated cervical vertebrae, and proximal
articular surface of metatarsal III that is shelf-like and medially deflected. Phylogenetic analysis recovers Leyesaurus as a basal sauropodomorph, sister taxon of Adeopapposaurus within the Massospondylidae. Moreover, the results suggest that massospondylids achieved a higher diversity than previously thought.

Conclusions/SignificanceOur phylogenetic results differ with respect to previous analyses by rejecting the massospondylid affinities of some taxa from the northern hemisphere (e.g., Seitaad, Sarahsaurus). As a result, the new taxon
Leyesaurus, coupled with other recent discoveries, suggests that the diversity of massospondylids in the southern hemisphere was higher than in other regions of Pangea. Finally, the close affinities of Leyesaurus with the Lower Jurassic Massospondylus suggest a younger age for the Quebrada del Barro Formation than previously postulated.

New information on the Protorosaurian Reptile Macrocnemus fuyuanensis from the Triassic of China

The new issue of JVP is out:

Jiang, D.-Y., Rieppel, O., Fraser, N. C., Motani, R., Hao, W.-C., Tintori, A., Sun, Y.-L., and Z.-Y. Sun. 2011. New information on the protorosaurian reptile Macrocnemus fuyuanensis Li et al., 2007, from the Middle/Upper Triassic of Yunnan, China. Journal of Vertebrate Paleontology 31: 2011-1237, DOI:10.1080/02724634.2011.610853

Abstract - A new specimen of the protorosaur Macrocnemus fuyuanensis, from the Zhuganpo Member of the Falang Formation at Fuyuan (Yunnan Province, southwestern China), is described and compared with Macrocnemus bassanii. The new specimen is the first in the genus Macrocnemus that clearly shows details of the preorbital region of the skull. A large, plate-like lacrimal is located in front of the tall, columnar prefrontal that defines the anterior margin of the orbit. A longitudinally oriented nasal groove extends along the anterior two-thirds of the snout, accommodating the external naris at its anterior part. A similar preorbital depression has previously been described for Dinocephalosaurus and it is also reported here for the first time in Tanystropheus. The new specimen confirms the status of Macrocnemus fuyuanensis as a species distinct from Macrocnemus bassanii on the basis of a humerus that significantly exceeds the radius in length. The occurrence of both Macrocnemus and Tanystropheus in southwestern China further underscores the close faunal affinities of the eastern and western Tethyan realms during the Middle and early Late Triassic.

Taphonomic Effects on the Stratigraphic Ranges of Rare Taxa in the Chinle Formation of Arizona

Loughney, K. M., Fastovsky, D. E., and W. G. Parker. 2011. Vertebrate fossil preservation in blue paleosols from the Petrified Forest National Park, Arizona, with implications for vertebrate biostratigraphy in the Chinle Formation. Palaios 26:700-719.

Abstract - Exposures of the Chinle Formation in Petrified Forest National Park (PEFO), Arizona, preserve one of the most important Upper Triassic terrestrial faunal assemblages in the world: in it are found key elements in the global and regional correlation of continental deposits of Upper Triassic age. Rare components of the Chinle Formation faunal assemblage, including dinosaurs and small-bodied amniotes, appear to be mostly restricted to distinctive blue-colored horizons observed at only a few sites in PEFO. The blue sites represent paleosols formed in fine-grained, abandoned channel fills and contrast markedly with red-colored floodplain deposits and paleosols that characterize most fossil localities in the Chinle Formation. The distinctive blue color is interpreted as a weathered feature of hydromorphically reduced iron. The coincidence of rare taxa and sites bearing the blue-colored paleosols suggests that the stratigraphic positions of the sites and the rare taxa they contain appear to relate to fluvial sequence tracts in PEFO and may not reflect the true stratigraphic ranges of these taxa.

Cranial Morphology of the Plagiosaurid Gerrothorax pulcherrimus as an Extreme Example of Evolutionary Stasis

Schoch, R. R. and F. Witzmann. 2011. Cranial morphology of the plagiosaurid Gerrothorax pulcherrimus as an extreme example of evolutionary stasis. Lethaia, DOI: 10.1111/j.1502-3931.2011.00290.x

Abstract - The plagiosaurid Gerrothorax pulcherrimus from the Triassic of Greenland and Germany is represented by skulls ranging from 4 to 12 cm in length and sheds light on ontogeny, individual variation, and variation in time and space. Ontogeny was remarkably stable in G. pulcherrimus, with the smallest known specimens resembling the adults closely in most features. A true ontogenetic change is evident in the ornament of dermal bones, in that the smallest specimens have ridges whereas in the successively larger ones, pustules spread over increasingly larger areas. The skull becomes proportionally longer, and the adductor chambers relatively narrower. The positive allometry of both the orbits and the interpterygoid vacuities suggests that the eye supporting musculature – rather than the jaw adductors – increased proportionally during growth. Individual, not age-related variation in the dermal skull roof affects partial fusion of parietals, presence and extent of the interfrontoparietal, and the morphological pattern of the posterior skull table. The ventral surface of the basal plate of the parasphenoid ranges from smooth over poorly to heavily ornamented or dentigerous. Considering the impressive longevity of more than 35 Myr, the morphological changes of G. pulcherrimus are minor. Our ecological interpretation for G. pulcherrimus is that it relied on the permanent presence of water, but was flexible with respect to the size and nature of the water body as well as to changes in salinity. The unparalleled extent of evolutionary stasis may therefore be based on the ecological flexibility of this morphologically so tightly constrained temnospondyl.

Vertebrate Fossils from the Marine Triassic of Austria

Krainer, K. Lucas, S. G., and M. Strasser. 2011. Vertebrate fossils from the Northalpine Raibl beds, Western Northern Calcareous Alps, Tyrol (Austria). Austrian Journal of Earth Sciences 104:97-106. [free pdf]

Abstract -

Aus den Nordalpinen Raibler Schichten des Karwendels und der Mieminger Kette in den westlichen Nördlichen Kalkalpen (Tirol,
Österreich) werden Vertebratenreste wie Fischzähne von Actinopetrygiern (
Fischzähne) und laterale Zähne von
beschrieben. Die Vertebratenreste wurden in Onkolithen und Schillagen gefunden, die in dunkle Tonschiefer eingeschaltet
sind. Wir interpretieren diese Lagen als hochenergetische Sedimente (Tempestite), entstanden durch Sturmereignisse in einem
inneren Schelfbereich. Die in dieser Arbeit dokumentierten Vertebratenreste der Raibler Schichten sind ein weiterer Nachweis typischer
Fisch- und Tetrapodentaxa, die in den Meeren der Mittel- und Obertrias in Westeuropa lebten.
Vertebrate fossils such as fish teeth derived from Actinopterygii (Saurichthys morphotype, Colobodus?, indeterminate) and lateral teeth of Paleobates (small sharks) as well as reptile fragments ascribed to Eusauropterygia? and Prolacertiformes are reported from the Northalpine Raibl Beds of the Karwendel and Mieming mountain ranges of the western Northern Calcareous Alps (Tyrol, Austria). The vertebrate fossils occur in oncolite and coquina beds that are intercalated in dark shales. We interpret these intercalated beds as high-energy sediments deposited during storm events (tempestites) in an inner shelf environment. The Raibl vertebrate fossils documented here add another well-established record of characteristic fish and tetrapod taxa that lived in the Middle-LateTriassic seaways that covered Western Europe.Saurichthys Morphotyp, Colobodus?, unbestimmbarePaleobates (kleine Haie) sowie Reptilienfragmente von Eusauropterygiern? und Prolacertiformes

New Findings on the Early Triassic Recovery of the Terrestrial Vertebrate Fauna - Redux

Here is the abstract and link to the new article and it is currently open access.

Irmis, R. B. and J. H. Whiteside. 2011.Delayed recovery of non-marine tetrapods after the end-Permian mass extinction tracks global carbon cycle. Proceedings of the Royal Society B (advance online publication) doi: 10.1098/rspb.2011.1895

Abstract - During the end-Permian mass extinction, marine ecosystems suffered a major drop in diversity, which was maintained throughout the Early Triassic until delayed recovery during the Middle Triassic. This depressed diversity in the Early Triassic correlates with multiple major perturbations to the global carbon cycle, interpreted as either intrinsic ecosystem or external palaeoenvironmental effects. In contrast, the terrestrial record of extinction and recovery is less clear; the effects and magnitude of the end-Permian extinction on non-marine vertebrates are particularly controversial. We use specimen-level data from southern Africa and Russia to investigate the palaeodiversity dynamics of non-marine tetrapods across
the Permo-Triassic boundary by analysing sample-standardized generic richness, evenness and relative abundance. In addition, we investigate the potential effects of sampling, geological and taxonomic biases on these data. Our analyses demonstrate that non-marine tetrapods were severely affected by the end-Permian mass extinction, and that these assemblages did not begin to recover until the Middle Triassic. These data are congruent with those from land plants and marine invertebrates. Furthermore, they are consistent with the idea that unstable low-diversity post-extinction ecosystems were subject to boom-bust cycles, reflected in multiple Early Triassic perturbations of the carbon cycle.

New Findings on the Early Triassic Recovery of the Terrestrial Fauna

Congratulations to Randall Irmis and Jessica Whiteside on this new study. This article is up on the Science Magazine website although the article is not up yet on the Royal Society Publishing website. I'll post the abstract and link when it appears.

http://news.sciencemag.org/sciencenow/2011/10/the-sunll-come-out-tomorrow-mayb.html

Long Bone Microstructure of Middle Triassic Pachypleurosaurids


Missed this article from May 2011 in the special issue of Compte Rendus Paleovol in honor of Dr. Armand de Ricqlès.
Hugi, J., Scheyer, T. M., Sander, P. M., Klein, N., and M. R. Sánchez-Villagra. 2011. Long bone microstructure gives new insights into the life of pachypleurosaurids from the Middle Triassic of Monte San Giorgio, Switzerland/Italy. Compte Rendus Palevol 10:413-426. doi:10.1016/j.crpv.2011.03.009



Abstract - The long bone microstructure of four pachypleurosaurid taxa from Monte San Giorgio (Switzerland/Italy) was studied. Pachypleurosaurids are secondarily aquatic reptiles that lived during the Middle Triassic in varying marine environments of the Tethys. All four pachypleurosaurids show high compactness values in their long bones based on a thick cortex and a calcified cartilaginous core, which remains in the medullary region throughout the ontogeny. Parts or even the entire embryonic bone layer composed of a mixture of woven fibered bone tissue and parallel-fibered bone tissue is preserved in both pachypleurosaurid genera. The rest of the cortex consists of lamellar-zonal bone tissue type. Differences in the microstructure of the bones between the pachypleurosaurids are reflected in the occurrence of remodelling processes, which, if present, affect the innermost growth marks of the cortex or the calcified cartilaginous core. Further variation is present in the spacing pattern of the growth cycles, as well as in the degree of vascularisation of the lamellar-zonal bone tissue type. Our data on the microstructure of the long bones support previous studies on morphology and facies distribution, which indicated different habitats and adaptation to a secondary aquatic lifestyle for each pachypleurosaurid taxon. Life history data furthermore reflect different longevities and ages at sexual maturity. The bone histological data of the stratigraphically youngest and oldest pachypleurosaurid species might indicate possible climate-dependant reproductive seasons similar to Recent lacertilian squamates.

Redescription of the Sail-backed Poposauroid Ctenosauriscus from the Early Triassic of Germany

Available now at PLoSONE is a redescription of this important historic Triassic taxon which is the namesake of a clade of sail-backed poposauroid archosaurs that have come into recent prominence given the discovery of a well-preserved specimen of Arizonasaurus babbitti in 2002. 

  

Butler, R. J., Brusatte, S. L., Reich, M., Nesbitt, S. J., Schoch, R. R., and J. J. Hornung. 2011. The sail-backed reptile Ctenosauriscus from the latest Early Triassic of Germany and the timing and biogeography of the early archosaur radiation. PLoS ONE 6(10): e25693. doi:10.1371/journal.pone.0025693

 

Background

Archosaurs (birds, crocodilians and their extinct relatives including dinosaurs) dominated Mesozoic continental ecosystems from the Late Triassic onwards, and still form a major component of modern ecosystems (>10,000 species). The earliest diverse archosaur faunal assemblages are known from the Middle Triassic (c. 244 Ma), implying that the archosaur radiation began in the Early Triassic (252.3–247.2 Ma). Understanding of this radiation is currently limited by the poor early fossil record of the group in terms of skeletal remains.

Methodology/Principal Findings

We redescribe the anatomy and stratigraphic position of the type specimen of Ctenosauriscus koeneni (Huene), a sail-backed reptile from the Early Triassic (late Olenekian) Solling Formation of northern Germany that potentially represents the oldest known archosaur. We critically discuss previous biomechanical work on the ‘sail’ of Ctenosauriscus, which is formed by a series of elongated neural spines. In addition, we describe Ctenosauriscus-like postcranial material from the earliest Middle Triassic (early Anisian) Röt Formation of Waldhaus, southwestern Germany. Finally, we review the spatial and temporal distribution of the earliest archosaur fossils and their implications for understanding the dynamics of the archosaur radiation.

Conclusions/Significance

Comprehensive numerical phylogenetic analyses demonstrate that both Ctenosauriscus and the Waldhaus taxon are members of a monophyletic grouping of poposauroid archosaurs, Ctenosauriscidae, characterised by greatly elongated neural spines in the posterior cervical to anterior caudal vertebrae. The earliest archosaurs, including Ctenosauriscus, appear in the body fossil record just prior to the Olenekian/Anisian boundary (c. 248 Ma), less than 5 million years after the Permian–Triassic mass extinction. These earliest archosaur assemblages are dominated by ctenosauriscids, which were broadly distributed across northern Pangea and which appear to have been the first global radiation of archosaurs.

National Fossil Day

Today is the 2nd annual observance of National Fossil Day. Be sure to check out the official website for lists of events and activities taking place near you, with the biggest event on the National Mall in Washington D. C.

Please join in the activities and have fun!

Visiting Triassic Park - Ischigualasto Parque Triasico in Argentina

Last month I was fortunate to be able to travel to Argentina for some research time and to attend and present at the Fourth Latin American Vertebrate Paleontology Conference in San Juan. Part of the meeting involved a field trip to the nearby Ischigualasto National Park which is famous for its exposures of Triassic rocks and for fossils of some of the earliest dinosaurs including Eoraptor and Herrerasaurus.  As I work at the other Triassic Park, Petrified Forest National Park in Arizona, I was really looking forward to this visit and it did not dissappoint. Below I've posted some photos highlighting my visit. 


 The visitors center includes mounts (below) and life reconstructions (above) of many of the animals found in Triassic strata in the park. There are also exhibits of actual bones.

 Outcrops of the Upper Triassic Ischigualasto Formation. The expanse of the exposures is incredible.

 Bones, the Ischigualasto is full of bones.
 Christian Sidor and Zhe-Xi Luo getting excited about a cynodont skull that Chris found.
 Another in-situ cynodont skull. They are extremely (and amazingly) common here.
 Rhynchosaur bones weathering out. Again, the amount of fossil material in the exposures is staggering. Amazingly rhynchosaurs and cynodonts are so common, they are usually not collected. Working in a formation (the Chinle) where these types of animals are relatively unknown, it was very difficult to leave this material behind.
The younger Los Colorados Formation above the Ischigualsto.

Ischigualsto Park and the Ischigualsto Formation are absolutely incredible and I hope to be able to return someday to make new discoveries.

Paleohistology of Rauisuchid Osteoderms

Yes, I am still in Argentina. I'd planned on posting a little more, especially since I visited Ischigualasto National Park and spent some hours prospecting in the Ischigualasto Formation (it did not disappoint) but I've been up to my eyeballs in aetosaur specimens and trying to keep myself fed (meals take a long time here), so forgive me. Meanwhile here is a paper I've been waiting on for awhile now regarding osteoderm histology of rauisuchids with comparisons to some other archosaur groups as well.

Scheyer, T. M. and J. B. Desojo. 2011. Palaeohistology and external microanatomy of rauisuchian osteoderms (Archosauria: Pseudosuchia). Palaeontology (advance online publication) DOI: 10.1111/j.1475-4983.2011.01098.xhttp://onlinelibrary.wiley.com/doi/10.1111/j.1475-4983.2011.01098.x/abstract

Abstract - The presence of postcranial dermal armour is plesiomorphic for Archosauria. Here, we survey the external microanatomy and histology of postcranial osteoderms (i.e. dorsal paramedian and caudal osteoderms) of rauisuchians, a widely distributed assemblage of extinct predatory pseudosuchians from the Triassic. The osteoderms of eight rauisuchian taxa were found to be rather compact bones, which usually lack significant bone remodelling or large areas of cancellous bone. The presence of highly vascularized woven or fibrolamellar bone tissue deposited in the core areas indicates higher growth rates during earlier life stages, whereas a more compact parallel-fibred bone matrix indicates reduced growth rates in later development. This pattern of change corroborates earlier studies on long bone histology. With the exception of a bone tissue found in the sample of Batrachotomus kupferzellensis, which might be the result of metaplastic ossification, the general mode of skeletogenesis is comparable with intramembraneous ossification. The lack of cancellous bone tissue and remodelling processes associated with bone ornamentation, as well as the predominantly intramembraneous mode of ossification, indicates that rauisuchian osteoderm formation differs profoundly from that of the osteoderms of the only extant pseudosuchian lineage, the crocodylians.

First Evidence of Aetosaurs from the Plateosaurus Quarry of Germany

Matzke, A. T., and M. W. Maisch. 2011. The first aetosaurid archosaur from the Trossingen Plateosaurus Quarry (Upper Triassic, Germany). Neues Jahrbuch für Geologie und Paläontologie – Abhandlungen (advance online publication) DOI: 10.1127/0077-7749/2011/0203http://www.ingentaconnect.com/content/schweiz/njbgeol/pre-prints/0203

Abstract -Two associated cervical paramedian osteoderms and one isolated paramedian osteoderm of an aetosaur from the famous Trossingen Plateosaurus Quarry are described. They represent the first evidence of aetosaurs from Trossingen as well as the stratigraphically youngest remains of this group from Germany. Therefore, the Trossingen assemblage consists now of four species level taxa. Hitherto only three species level taxa were known from this quarry. Plateosaurus longiceps and Proganochelys quenstedti from complete specimens as well as one tooth of cf. Liliensternus. The finds indicate that more small- to medium-sized taxa may be present in the Trossingen Quarry.

New Capitosaur from the Middle Triassic of Spain

I'm still in Argentina. In San Juan now at the IV Congreso Latinamericano Paleontologia de Vertebrados. Yesterday was the early theropod symposium and many crocodylomorph talks. The basal archosaurs symposium starts today and runs through tommorrow. Etiquette precludes me from directly posting on details of the talks; however, I may find some willing to let me share.  In the meantime here is a new temnospondyl paper:

Fortuny, J., Galobart, À, and C. De Santisteban. 2011. A New Capitosaur from the Middle Triassic of Spain and the Relationships within the Capitosauria. Acta Palaeontologia Polonica 56:553:556. http://www.bioone.org/doi/abs/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 CyclotosaurusTatrasuchus and EryosuchusMastodonsaurus clades.

Candelariodon barberenai, a New Cynodont from the Middle Triassic of Brazil

Oliveira, T. V., Schultz, C. L., Soares, M. B., and C. N. Rodrigues. 2011. A new carnivorous cynodont (Synapsida, Therapsida) from the Brazilian Middle Triassic (Santa Maria Formation): Candelariodon barberenai gen. et sp. nov. Zootaxa 3027: 19–28.

Abstract - A new small cynodont, Candelariodon barberenai gen. et sp. nov., from the Middle Triassic of Brazil (Santa Maria Formation) is reported. The new taxon is represented by a partial mandible having some complete teeth. The morphology of the dentary and splenial is similar to other carnivorous cynodonts, except for the absence of the angular process of the dentary. The anterior-most lower teeth are slightly expanded buccolingually with a tall and posteriorly curved main cusp and one or two accessory cusps. The posterior-most preserved lower postcanine, however, has lingual and buccal rows of cusps, each formed by four anteroposteriorly aligned cusps, separated by a shallow basin. This tooth resembles the posterior-most lower teeth of Aleodon Crompton 1955 from the Middle Triassic of Tanzania, but the anterior-most teeth of Candelariodon and Aleodon are essentially different. In this context, the phylogenetic relationships of the new taxon remain unclear until the discovery of more informative material.

Day 1 - Buenos Aires - Museo Argentino de Ciencias

I'm now in Buenos Aires having arrived yesterday. I was fortunate to have the same flight as Casey Holliday (although he was bumped up to first class!) so we travelled together the first day here. Our first day was spent at the Museo Argentino de Ciencias Naturales (MACN) with me looking at aetosaur skulls (courtesy of Dra. Julia Desojo) and Casey looking at some crocodylian skulls. Had an energetic lunch with Julia and Oliver Rauhut (who was also visiting).  Here is a photo of Julia and Oliver in Julia's office trying to work on some research despite our repeated intrusions and partaking of the local beverage of choice.



Here is a photo of the Museo Argentina de Ciencias Naturales.


Beautiful skull of the aetosaur Neoaetosauroides engaeus.



Day 2: Intense aetosaur discussion with Julia Desojo and examination of a new taxon she is proposing.

IV Congresso Latino-Americano de Paleontologia de Vertebrados

I'm off to San Juan Argentina to attend and present two talks at the IV Congresso Latino-Americano de Paleontologia de Vertebrados. I'm also planning to do some aetosaur research in Buenos Aires and San Miguel de Tucuman. An added bonus is a field trip to Ischigualasto National Park.  This years meeting promises to be well attended with lots of great talks. In addition there are two symposia (Triassic and Jurassic theropods and basal archosaurs) heavy on Triassic research. You can read more about the meeting here:

http://www.congresopaleo.com.ar/bin-debug/congreso.html

Hopefully I'll see many of you there!

New Deep Bodied Vertebrate from the Middle Triassic of China

Thanks to Ben Creisler for pointing this new paper out to me. I know the post title is slightly misleading, but how many of you would have come here if I had put "deep-bodied fish"? ;)

This is very well preserved specimen and pretty cool, admit it. :).

Xu, G. -H., and F.- X., Wu. 2011. A deep-bodied ginglymodian fish from the Middle Triassic of eastern Yunnan Province, China, and the phylogeny of lower neopterygians. Chinese Science Bulletin online first. DOI: 10.1007/s11434-011-4719-1. 

 

Abstract - The Ginglymodi are a group of ray-finned fishes that make up one of three major subdivisions of the infraclass Neopterygii. Extant ginglymodians are represented by gars, which inhabit freshwater environments of North and Central America and Cuba. Here, we report the discovery of well-preserved fossils of a new ginglymodian, Kyphosichthys grandei gen. et sp. nov., from the Middle Triassic (Anisian) marine deposits (Guanling Formation) in Luoping, eastern Yunnan Province, China. The discovery documents the first known fossil record of highly deep-bodied ginglymodians, adding new information on the early morphological diversity of this group. The studies of functional morphology of extant deep-bodied fishes indicate that Kyphosichthys is not a fast swimmer but has a good performance in precise maneuvering, representing a morphological adaptation to structurally complex habitats (e.g. thick macrophyte beds, rocky areas, or coral reefs), which differs from the other members of this group. A cladistic analysis with the new fish taxon included supports the hypothesis that the Ginglymodi are more closely related to the Halecomorphi than to the Teleostei. Represented by Felberia, Kyphosichthys, and Dapedium, a highly deep and short fish body type has independently evolved at least three times in the stem-group neopterygians, ginglymodians, and basal teleosts within the lower neopterygians of the Triassic.

Mesozoic Shark Nurseries - Evidence from the Triassic of Kyrgyzstan

Very cool paper, especially since the Chinle Formation in Petrified Forest National Park also contains shark egg capsules (Palaeoxyris). The Petrified Forest specimens are the only ones known from North America.

Fischer, J., Voigt, S., Schneider, J. W., Buchwitz, M., and  & S. Voigt. 2011. A selachian
freshwater fauna from the Triassic of Kyrgyzstan and its implication for Mesozoic shark nurseries. Journal of Vertebrate Paleontology 31:937-953.

Abstract - Habitat partitioning and site fidelity of spawning grounds are well-documented phenomena in extant selachians, but little is known about the reproductive strategies of their fossil relatives. Here we describe the selachian fauna of the Middle to Late Triassic Madygen Formation in southwestern Kyrgyzstan, Central Asia, based on several dozen tooth crowns and egg capsules. The material is assigned to three new taxa: Lonchidion ferganensis, sp. nov., and Palaeoxyris alterna, sp. nov., being teeth and egg capsules of hybodontid sharks, and Fayolia sharovi, sp. nov., being egg capsules of probable xenacanthids. Teeth of L. ferganensis, sp. nov., were almost exclusively found in pelecypod-rich shallow lacustrine mudstones and belong to juvenile individuals. Oxygen and strontium isotope data of tooth enameloid indicate freshwater conditions of the ambient water at the time of tooth mineralization. The egg capsules are common findings in near-shore lake deposits as well. Considering the mass co-occurrence of juvenile teeth and egg capsules in the study area, we propose that hybodontid/ xenacanthid sharks recurrently occupied littoral zones of the Madygen lake for spawning. The small number of full-grown individuals points to habitat partitioning of juveniles and adults wherefore the study site is interpreted as a shark nursery. The oviposition strategies inferred from this fossil example are remarkably similar to those of modern sharks, suggesting that the reproductive patterns seen in extant sharks originated well before the Cenozoic.
http://dx.doi.org/10.1080/02724634.2011.601729

LACM Dinosaur Institute Hiring Paid Intern

Dinosaur Institute hiring paid intern. Please pass along.

Feel free to pass this along to any interested parties/mailing lists.

The Dinosaur Institute at the Los Angeles County Natural History Museum is currently seeking applicants for Proyecto Dinosaurios, a 1-year paid internship designed to encourage under-represented students to pursue careers in the geosciences. In order to apply, students must 1) currently be enrolled in a 2-yr community or junior college, 2) be a minority, preferably hispanic, 3) be eligible to work in the US (citizen or permanent resident), and 4) be interested in the sciences.

It's short notice, but if you know of any potential applicants please pass the information on to them. The application is due Sept 16, so passing this along soon would be greatly appreciated. Feel free to contact me (theropods@gmail.com) with any questions or interest and I'll pass it on.

-JTH
The Dinosaur Institute does some work in the Chinle at Petrified Forest as well as many other places.  Maybe we'll see the sucessful applicant here for a little bit.

New Capitosaur from the Early Triassic of Poland

Sulej, T., and G. Niedźwiedzki. in press. A new large capitosaur temnospondyl amphibian from the Early Triassic of Poland. Acta Palaeontologica Polonica available online 09 Sep 2011 doi:10.4202/app.2011.0025
 

Abstract - The Early Triassic record of the large capitosaur amphibian genus Parotosuchus is supplemented by new material from fluvial deposits of Wióry, southern Poland, corresponding in age to the Detfurth Formation (Spathian; late Olenekian) of the Germanic Basin. The skull of the new capitosaur shows an “intermediate” morphology between that of Parotosuchus helgolandicus from the Volpriehausen - Detfurth Formation (Smithian; early Olenekian) of Germany and the slightly younger P. orenburgensis from European Russia. These three species may represent an evolutionary lineage that underwent a progressive shifting of the jaw articulation anteriorly. The morphology of the Polish form is distinct enough from other species of Parotosuchus to warrant erection of a new species. The very large mandible of [new taxon name removed until formal publication] indicates that this was one of the largest tetrapods of the Early Triassic. Its prominent anatomical features include a triangular retroarticular process and an elongated base of the hamate process.

Petrified Forest National Park Adds 26,000 Acres to Protect Triassic Fossils

Some of the big news today in northeastern Arizona is the announcement that Petrified Forest National Park has purchased over 26,000 acres of private land as part of its ongoing expansion effort authorized by Congress in 2004. These new lands (the Paulsell or Hatch Ranch) mostly lie to the east of the existing park, but also includes about 8 square miles west of the park boundary. These lands are rich in fossil resources and have been worked in the past by the University of California (Berkeley), the Smithsonian, the American Museum of Natural History, and most recently by the University of Texas at Austin. The park hopes to continue these partnerships and is excited regarding the information this land acquisition will provide regarding the paleontology of the Late Triassic. Furthermore, the are strata cropping out on these lands that are not exposed within the old park boundary, significantly enhancing our understanding of the local stratigraphy.

You can read a little more about this here and here.

More on the Paleoecology of Triassic Turtles

Benson, R. B. J., Domokos, G., Várkonyi, P. L., and R. R. Reisz. 2011. Shell geometry and habitat determination in extinct and extant turtles (Reptilia: Testudinata). Paleobiology 37:547-562. doi: 10.1666/10052.1
Abstract - A variety of means, including forelimb proportions and shell bone histology have been used to infer the paleoecology of extinct turtles. However, the height-to-width ratio of the shell (as a one-parameter shell model) has been dismissed because of its unreliability, and more complex aspects of shell geometry have generally been overlooked. Here we use a more reliable, three-parameter geometric model of the shell outline in anterior view as a means to assess turtle paleoecology. The accuracy of predictions of extant turtle ecology based on our three-parameter shell model is comparable to that derived from forelimb proportions when distinguishing between three ecological classes (terrestrial, semiaquatic, and aquatic). Higher accuracy is obtained when distinguishing between two classes (terrestrial and non-terrestrial), because the contours of aquatic and semiaquatic turtles are often very similar. Our model classifies Proterochersis robusta, a stem turtle from the Late Triassic of Germany, as non-terrestrial, and likely semiaquatic. Our method, combined with inferences based on limb proportions, indicates a diverse range of ecotypes represented by Late Triassic stem turtles. This implies that the ecological diversification of stem-group turtles may have been rapid, or that a substantial period of currently cryptic diversification preceded the first fossil appearance of the turtle stem lineage during the Late Triassic.

High Latitute Triassic Flora from Antarctica

Escapa, I. H., Taylor, E. L., Cúneo, R., Bomfleur, B., Bergene, J., Serbet, R., and  T. N. Taylor. 2011. Triassic floras of Antarctica: plant diversity and distribution in high paleolatitude communities. Palaios 26:522-544.
Abstract - Continental Triassic sequences in Antarctica are among the most continuous and best represented in Gondwana. Triassic fossil plants have been collected sporadically from Antarctica since the beginning of the twentieth century, but our knowledge of the vegetation during this time has dramatically increased during the last three decades. Here we review the fossil record of Triassic plants as representatives of natural groups from sites along the Transantarctic Mountains, using the fossils as evidence for successive vegetational changes through the Triassic, taking into account that these plant communities were living under particular high-latitude (70° or higher) paleoclimatological conditions, including a polar light regime. Even though our knowledge of the Triassic floras of Antarctica is still incomplete, this survey shows that these floras were remarkably diverse. Lycopsids, equisetaleans, ferns, seed ferns, ginkgoaleans, and conifers were major components of the landscape in Antarctica during this time. The diversity of gymnosperms is exceptional, with almost every major clade of seed plants present, despite the high paleolatitude; however, each clade is often represented by only one or a few genera. The occurrence of permineralized peat, along with compression-impression floras, has increased our knowledge of the morphology, reproductive biology, and evolution of many of the plants in these floras. In general, floral changes in Antarctica during the Triassic can be recognized elsewhere in Gondwana, especially in South America, although a strict correlation based on macrofossils is still not possible. Thus, this contribution represents the first attempt to bring together information on Triassic floras from continental Antarctica (excluding the Antarctic Peninsula) within a biostratigraphic framework and thereby to compare these floras with those from lower latitudes.

PEFO Summer Fieldwork Parts 3 and 4

Susan has the rest of her summer exploits in the Chinle Formation up at The Forgotten Archosaurs (Parts three and four). Reading through makes me wish I was there ;). Isn't she glad that she wrote everything down?

Complex Tetrapod Burrows from the Middle Triassic of Morocco

Too bad there are not any body fossils associated with this find....
Voigt, S., Schneider, J. W., Saber, H.,  Hminna, A.,  Lagnaoui, A.,  Klein, H.,  Brosig, A., and J. Fischer. 2011. Complex tetrapod burrows from Middle Triassic red beds of The Argana Basin (Western High Atlas, Morocco). Palaios 26:555-556.

Abstract - Although burrowing ability has been widespread in tetrapods for more than 300 million years, subsurface dwelling structures that indicate communal behavior are poorly evidenced from pre-Cenozoic strata. Here we present recently discovered tetrapod burrows from Middle Triassic red beds of the Argana Basin in central Morocco, whose complexity suggests an origin by gregarious animals. The well-preserved burrows occur in interbedded mudstones and sandstones interpreted as channel and overbank deposits of ephemeral, braided streams. All burrows originate from the top of thick-bedded sandstones and descend as moderately inclined (10°–30°), partially spiral tunnels to laterally extended, branched chambers in underlying mudstones. Tunnel segments are biconvex to planoconvex in cross section, up to 20 cm wide and 12 cm in maximum height and exhibit transverse scratch marks along the ceilings and sidewalls. Distinctive burrow characteristics include a laterally sinuous geometry (wavelength λ  =  38–45 cm; amplitude A  =  5–10 cm) of the tubelike passages and the presence of grouped alcoves in terminal chambers. We attribute the burrows to procolophonids or therapsids based on closely associated tetrapod tracks and the limited diameter of the excavations. Our findings represent the second oldest record of communal fossorial behavior by tetrapods and the oldest example from low-latitude areas. Beyond providing refuge from predators, these elaborate underground structures probably functioned as a buffer against diurnal or seasonal variations of air temperature and humidity in a semiarid habitat that was situated just north of the paleoequator.

Summer Fieldwork at PEFO pt. 2

Susan Drymala has another post up at The Forgotten Archosaurs. I like the photo of the seat belt restraining the fossil jacket.

New Vertebrate Locality from the Lower Triassic of Brazil

The taxonomic diversity of these Gondwanan sites is incredible. I'd love to find even fragmentary procolophonids and synapsids in the Chinle.

Dias-da-Silva, S., and Á. A. S. da-Rosa. 2011. Granja Palmeiras, a new fossiliferous site for the Lower Triassic of southern Brazil. Revista Brasileira de Paleontologia 14(2):157-168 doi:10.4072/rbp.2011.2.04

Abstract - A new fossiliferous locality, Granja Palmeiras, is described for the Sanga do Cabral Formation (Lower Triassic of Southern Brazil, Rosário do Sul Group, Paraná Basin). It consists on orange and reddish fine sandstones, with sandy and calcareous concretions and intercalated fossiliferous intraformational conglomerates. Its fossils are fragmentary and badly preserved. Nevertheless, among the 46 specimens collected so far, putative actinopterygians,temnospondyls, procolophonoids, archosauromorphs, and non-mammalian cynodonts were identified. Besides, several non-diagnostic appendicular elements are ascribed to Tetrapoda indet. The fossiliferous content found in Granja Palmeiras can provide a valuable new framework for future correlation with other Lower Triassic South American units as well as other continental tetrapod- bearing deposits from Gondwana.

RESUMO – Uma nova localidade fossilífera, Granja Palmeiras, é descrita para a Formação Sanga do Cabral (Triássico Inferior do sul do Brasil, Grupo Rosário do Sul, bacia do Paraná). Consiste em arenitos finos alaranjados e avermelhados, com concreções carbonáticas e arenosas, e conglomerados intraformacionais intercalados. Os fósseis se apresentam fragmentários e em mal estado de preservação. Mesmo assim, dentre os 46 espécimes coletados até o momento foram identificados restos de actinopterígios, temnospôndilos, procolofonóides, arcossauromorfos e prováveis cinodontes não-mamalianos. Além destes, vários elementos apendiculares não diagnósticos são atribuídos a Tetrapoda indet. O conteúdo fossilífero registrado na Granja Palmeiras pode fornecer informações valiosas para a correlação com outras unidades do Triássico Inferior sul-americano, bem como com outras localidades gondwânicas de outras regiões do globo.

Revisiting Our Summer of Fieldwork at PEFO

It's been a pretty slow week for Triassic-themed papers and events, and I'm pretty swamped trying to complete a couple of manuscripts as well as getting ready for upcoming meetings in Argentina and Las Vegas.

Luckily Susan Drymala is back up and blogging at the Forgotten Archosaurs and has an excellent new post on the beginning of our 2011 summer fieldwork. Please go check it out.

CAMP Magnetostratigraphy Revisited

New paper in which the results suggest that either the SA5.r magnetozone from St. Audrie's Bay is not recorded in North American and Moroccan CAMP deposits or that the SA5.r is not reliable or useful for global-scale correlations. This has implications on the timing of the CAMP eruptions in relation to the Triassic-Jurassic boundary as well as correlations into non-marine sequences. This paper also provides a new paleo pole hypothesis for CAMP deposits in Morocco, which is more similar than past poles recovered for that unit to those determined for the North American sequence.

Font, E., Youbi, N., Fernandes, S., El Hachimi, H., Kratinova, Z., and Y. Hamim. 2011. Revisiting the magnetostratigraphy of the Central Atlantic Magmatic Province (CAMP) in Morocco. Earth and Planetary Science Letters, corrected proof. doi:10.1016/j.epsl.2011.07.007

Abstract - The origin of the Triassic–Jurassic (Tr–J) mass extinction is still a matter of debate: proponents of the idea that continental flood basalts of the Central Atlantic Magmatic Province (CAMP) are responsible for the crisis are opposed by those who favor an extraterrestrial origin linked to the impact of meteorite. Principal limitations reside in the difficulty to date and correlate CAMP lavas with the marine realm turnover. One argument widely used to suggest that CAMP lavas pre-dated the Tr–J boundary in Morocco is based on the presence of two brief magnetic reversals in the intermediate units of the Tiourjdal and Oued Lahr sections (Morocco) that were correlated to the E23r chron from the Newark basin and to the SA5n.2r/3r and SA5r chrons of the Saint Audrie Bay [Knight, K.B., Nomade, S., Renne, P.R., Marzoli, A., Betrand, H., Youbi, N., 2004. The Central Atlantic Magmatic Province at the Triassic–Jurassic boundary: paleomagnetic and 40Ar/30Ar evidence from Morocco for brief, episodic volcanism. Earth and Planetary Science Letters 228, 143–160]. However the primary origin for these negative (reverse) magnetic components is questionable since no field or reversal test was provided to constrain the primary character of the remanence as well as because the small number of samples. Here we have conducted a detailed paleomagnetic and magnetic mineralogy study of the interbedded limestones of the Tiourjdal section and of other CAMP lavas sections where the intermediate unit is complete, namely the Tizi El Hajaj, Jbel Imzar and Aït Ourir sections, to better constrain the origin and stratigraphic location of these negative magnetic components. We show that the interbedded limestones of the Tiourjdal section were entirely remagnetized by chemical processes via acid and oxidizing hydrothermal fluids generated by eruptions of CAMP lavas. In addition, magnetostratigraphic data of the Tizi El Hajaj, Jbel Imzar and Aït Ourir sections show that the entire intermediate unit encompassed a positive (normal) magnetic interval. A good quality paleomagnetic pole for the CAMP lava in Morocco is then provided (Plat = 60.0°; Plong = 241.6°; A95 = 2.6; N = 99) that is now in better agreement with its trans-Atlantic counterpart.

More Thoughts on Smok

Brian Switek has a really good post titled "The Dinosaur That Wasn't" over at Dinosaur Tracking.

New Isotopic Dates for Strata in the Late Triassic Chinle Formation, Petrified Forest National Park


I'm thrilled that this is finally out, along with the recent Irmis et al. paper. This new paper by Ramazani et all provides high-precision isotopic dates for a variety of stratigraphicl levels of the Chinle Formation in Petrified Forest National Park. Furthermore it provides the first dates for the Mesa Redondo and Owl Rock Members which essentially contrain the entire park section. The Mesa Redondo date is particularly important because it comes close to representing the base of the Chinle Formation in Arizona (see stratigraphic discussion in Irmis et al., 2011). The stratigraphic sequence and scheme used for this study is based upon independent work conducted by Dr. David Fastovsky of the University of Rhode Island and some of his students, as well as work done by a group from Baylor University.  Thus it doesn't match the current park stratigraphic nomenclature introduced by Martz and Parker (2010) and Parker and Martz (2011). Still the two are close and if anyone has any questions where these new dates fit into our scheme please contact me.

Some important points made by the paper:

- Chinle deposition in Petrified Forest ranged from about 225 - 208 million years ago or a duration of 17 million years.

- There is not enough stratal thickness in the Sonsela Member to account for the elapsed amount of time, so there must be many hiatuses in this unit.

- Despite the purported presence of numnerous hiatuses in the Sonsela none of them are large-scale, and there is little evidence for a sizable regional unconformity (i.e., the TR-4). [Note that this is also supported by other stratigraphic and biostratigraphic data].

- These authors argue that the basal Chinle date demonstrates overlap between the Chinle and Ischigualasto formations, suggesting that the rise of early dinosaurs was not diachronous (but see Irmis et al., 2011).


Ramezani, J., Hoke, G. D., Fastovsky, D. E., Bowring, S. A., Therrien, F., Dworkin, S. I., Atchley, S. C., and L. C. Nordt. 2011. High-precision U-Pb zircon geochronology of the Late Triassic Chinle Formation, Petrified Forest National Park (Arizona, USA): Temporal constraints on the early evolution of dinosaurs. Geological Society of America Bulletin. First published online August 19, 2011, doi: 10.1130/B30433.1 

Abstract - The Triassic successions of the Colorado Plateau preserve an important record of vertebrate evolution and climate change, but correlations to a global Triassic framework are hampered by a lack of geochronological control. Tuffaceous sandstones and siltstones were collected from the Upper Triassic Chinle Formation exposed in the Petrified Forest National Park, Arizona, USA, within a refined stratigraphic context of 31 detailed measured sections. U-Pb analyses by the isotope dilution–thermal ionization mass spectrometry (ID-TIMS) method constrain maximum depositional ages for nine tuffaceous beds and provide new insights into the depositional history of the Chinle fluvial system. The base of the Blue Mesa Member of the Chinle Formation is placed at ca. 225 Ma, and the top of the Petrified Forest Member is placed at 208 Ma or younger, bracketing an ∼280-m-thick section that spans nearly the entire Norian Stage of the Late Triassic. Estimated sediment accumulation rates throughout the section reflect extensive hiatuses and/or sediment removal by channel erosion. The new geochronology for the Chinle Formation underscores the potential pitfalls of correlation of fluvial units based solely on lithostratigraphic criteria. A mid-Norian age (ca. 219–213 Ma) for the distinctive Sonsela conglomeratic sandstone bed constrains the Adamanian-Revueltian land vertebrate faunachron boundary. Our new data permit a significant time overlap between the lower Chinle sequence and the dinosauromorph-rich Ischigualasto Formation of northwestern Argentina. Near-contemporaneity of the trans-American deposits and their faunal similarities imply that early dinosaur evolution occurred rapidly across the Americas.