Field of Science

New Study on the Late Triassic Pollen Record at the Petrified Forest National Park, Arizona, USA

This is a new study of the palynology of the Chinle Formation of Petrified Forest National Park that fills in a previous sampling gap caused by reevaluation of the local stratigraphy. The study finds three pollen assembalge biozones that correspond to the two zones previously recovered by Litwin et al. (1991). Two main points of the paper are: 1) these faunal zones no longer pertain to the Carnian/Norian boundary as recent dating of the Chinle Formation in conjunction with a recalibration of the Late Triassic timescale demonstrates that the Chinle Formation is Norian-Rhaetian in age (Irmis et al., 2011; Ramezani et al., 2011); 2) the floral turnover roughly corresponds stratigraphically with the faunal turnover precisely located in the park by Parker and Martz (2011). Potential causal mechanisms remain under investigation.

Reichgelt, T., Parker, W. G., Martz, J. W., Conrad, J. G., van Konijnenburg-van Cittert, J. H. A., and W. M. Kürschner. 2013. The palynology of the Sonsela Member (Late Triassic, Norian) at Petrified Forest NP, Arizona, USA. Review of Palaeobotany and Palynology 189:18-28.

Abstract - Recent paleontological investigations and lithostratigraphic revisions reveal a marked biotic turnover zone within the continental deposits of the Sonsela member of the Chinle Formation (Late Triassic, Norian) at Petrified Forest National Park, USA. Within the Sonsela member we found three pollen assemblage biozones: Zone II (90.5–94 m above the Mesa Redondo member) contains a relatively diverse palynological assemblage, with a mix of pteridosperms, voltzialean and some Mesozoic conifers. Following a 2.3 m hiatus, Zone IIIa (96–97.5 m) is characterized by a decrease in pteridosperms and Mesozoic conifers and a drop in voltzialean conifer diversity. The alleged voltzialean conifer pollen Klausipollenites gouldii was dominant in this part of the assemblage and a significant rise in spores and cycad pollen was also evident. In Zone IIIb (97.5–98.5 m) diversity increases and several taxa, which were absent in Zone IIIa reappear, although K. gouldii remained the most abundant taxon. The transition between the palynological assemblages Zones II and IIIa coincide approximately (within a ~2.5 m interval) with a documented faunal turnover. The floristic assemblages suggest that the climate of the south-western United States during the Norian was most likely semi-arid and highly seasonal, despite being located at tropical latitudes, with aridification occurring towards the end-Triassic as the continent drifted northwards and global volcanism increased. The gymnosperm dominated palynofloral assemblage as opposed to the fern- and horsetail-dominated macrofossil record of the Sonsela member of the Chinle Formation, conforms to a semi-arid upland environment alternated by riparian, swampy lowland.

REFERENCES: 

Irmis, R. B., Mundil, R., Martz, J. W., and W. G. Parker. 2011. High-precision U-Pb zircon ages from the Chinle Formation of New Mexico, USA: Implications for Late Triassic vertebrate biostratigraphy and the rise of dinosaurs. Earth and Planetary Science Letters 309:258-267.

Litwin, R. J., Traverse, A., and S.R. Ash. 1991.  Preliminary palynological zonation of the Chinle Formation, southwestern U.S.A., and its correlation to the Newark Supergroup (eastern U.S.A.).  Review of Palaeobotany and Palynology 68:269-287.

Parker, W. G., and J. W. Martz. 2011. Constraining the stratigraphic position of the Late Triassic (Norian) Adamanian Revueltian faunal transition in the Chinle Formation of Petrified Forest National Park, Arizona. Earth and Environmental Transactions of the Royal Society of Edinburgh 101:231-260. 

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): Temporal constraints on the early evolution of dinosaurs. Geological Society of America Bulletin 123:2142-2159.

Diverse Tetrapod Track Assemblages from the Late Triassic of Morocco

Lagnaoui, A. Klein, H., Voigt, S., Hminna, A., Saber, H., Schneider, J. W., and R. Werneburg. 2012. Late Triassic Tetrapod-Dominated Ichnoassemblages from the Argana Basin (Western High Atlas, Morocco). Ichnos 19:238-253. 
DOI:
10.1080/10420940.2012.718014


Abstract - Diverse tetrapod track assemblages with Scoyenia invertebrate traces were discovered in the Triassic Timezgadiouine and Bigoudine formations of the Argana Basin (Western High Atlas, Morocco). The ichnofossils occur in alluvial plain sandstones and mudstones of the Irohalène Member (T5) and Tadart Ouadou Member (T6) considered Carnian-Norian in age by vertebrate remains and palynomorphs. Tetrapod footprints are assigned to ApatopusAtreipus-Grallator,Eubrontes isp., Parachirotherium, cf. Parachirotherium postchirotherioidesRhynchosauroides ispp., and Synaptichnium isp. They can be referred to lepidosauromorph/ archosauromorph, basal archosaur, and dinosauromorph trackmakers. Apatopus represented by 11 tracks of a more than 4 m long trackway, is recorded for the first time outside of North America and Europe. The assemblage concurs with the proposed Late Triassic age of the track-bearing beds by the occurrence of ApatopusAtreipus-Grallator, and Eubrontes. If this is accepted, the stratigraphic range of Synaptichnium and Parachirotherium, hitherto known only from Early or Middle Triassic deposits, has to be extended to the Carnian-Norian. The occurrence of Eubrontes in the Irohalene Member (T5) provides further evidence for large theropods in pre-Jurassic strata. All assemblages are referred to the Scoyenia ichnofacies indicating continental environments with alternating wet and dry conditions.

Finally a Dinosaur Textbook with a Section on Dinosaur Origins! Dinosaurs: A Concise Natural History

In 2010 when I reviewed the first edition of Fastovsky and Weishampel "Dinosaurs: a Concise Natural History" for the Journal of Vertebrate Paleontology I gave it a good review, recommending it for classroom use.  However, one complaint I had was that as a book on dinosaurs it had almost no coverage of dinosaur origins.  David Fastovsky took note and assured me that the next edition would remedy this. 

Well I'm happy to say that the second edition is out and does indeed have a much expanded section on dinosaur origins. Thanks to David and David for not taking my constructive criticism too hard and adding this section. In my opinion this makes what I think is the best dinosaur textbook available even better. 

Rediscovered Specimen Draws Dinosaur Origins Down Into the Middle Triassic

I've been peripherally involved in the recent renaissance regarding dinosaur origins since my discovery of the skeleton of Revueltosaurus callenderi in 2004 and the subsequent recognition that it was not a dinosaur. With my good friends and colleagues Sterling Nesbitt and Randall Irmis, I proceeded to reexamine much of the Late Triassic dinosaur record using an apomorphy-based approach emphasized by UT Austin professor Chris Bell and his colleagues for Neogene vertebrates. Our findings were that Triassic dinosaurs were actually rarer than previously believed, especially in North America. In addition, extensive fieldwork by Sterling and Randy led to the discoveries of Dromomeron romeri, Tawa hallae, and Asilisaurus kongwe, filling in some key gaps in our understanding of the early diversification of the Ornithodira.  Nonetheless it has become readily apparent that many important specimens crucial to this issue were not weathering out of outcrops in the field, but rather were sitting un- or misidentified in museum collections around the globe. Our new understanding of character states and polarities for early diverging dinosauriforms provided us with specific search criteria leading to the discoveries and/or reinterpretations of taxa such as Eucoelophysis baldwini, Dromomeron gregorii, Technosaurus smalli, Daemonosaurus chauliodus, and of course Effigia okeeffae, all from previously collected material including fossils collected for Edward Cope in the 1800s. Furthermore, Randy's work found that the rise of dinosaurs was diachronous, although the timing is still poorly understood.

The discovery of the silesaurid Asilisaurus kongwe (published in 2010) pulled the split between Silesauridae and Dinosauria into the Middle Triassic creating a significant ghost lineage for Dinosauria as the earliest known bona fide dinosaurs do not appear until the end of the Carnian stage of the Late Triassic. Amazingly it appears that we did not need to wait very long for this ghost lineage to be filled.

Today's issue of Biology Letters has a paper by Sterling Nesbitt, Paul Barrett, Sarah Werning, Christian Sidor, and the late Alan Charig on a probable new dinosaur from the Middle Triassic of Tanzania. Even more amazing is that this is not a new specimen, but was actually collected in the 1930s, and never described, except in Charig's 1950s dissertation, until today. Charig named the new specimen Nyasasaurus parringtoni and until now this name has been a nomen nudum.

Known from a partial humerus and several vertebrate (three cervical, five presacral and three sacral), reanalysis places Nyasasaurus as either a dinosaur or as the sister taxon to Dinosauria. The humerus bears a ventrally elongated deltopectoral crest with a deflected apex, both synapomorphies of Dinosauria. The cervical vertebrae are elongate and possess deep lateral fossae, consistent with character states found in dinosaurs. The presence of three sacral vertebrae, although not restricted to Dinosauria, also supports this placement. This interpretation is supported not only by a phylogenetic analysis but also by bone histology, which shows high, continuous growth rates similar to that of early diverging dinosaurs. 

This material suggests that dinosaurs probably appeared in the fossil record 10 to 15 million years earlier than we expected. Furthermore, Nesbitt et al. argue that this strongly supports the hypothesis that dinosaurs were not a dominant group during their early history. Finally, Nyasasaurus also provides more support for a Gondwanan origin of dinosaurs.


One thing that is now definitely clear is that workers interested in dinosaur origins will need to spend more time in Middle Triassic terrestrial units. Back in 2004 I don't think any of us fathomed what discoveries and interpretations the next decade would bring. As I often state, it is not necessarily what we already know that dirves our work, but what is still out there for us to learn.


Nesbitt, S. J., Barrett, P. M., Werning, S., Sidor, C. A., and A. J. Charig. 2012. The oldest dinosaur? A Middle Triassic dinosauriform from Tanzania. Biology Letters.
 

Abstract - The rise of dinosaurs was a major event in vertebrate history, but the timing of the origin and early diversification of the group remain poorly constrained. Here, we describe Nyasasaurus parringtoni gen. et sp. nov., which is identified as either the earliest known member of, or the sister-taxon to, Dinosauria. Nyasasaurus possesses a unique combination of dinosaur character states and an elevated growth rate similar to that of definitive early dinosaurs. It demonstrates that the initial dinosaur radiation occurred over a longer timescale than previously thought (possibly 15 My earlier), and that dinosaurs and their immediate relatives are better understood as part of a larger Middle Triassic archosauriform radiation. The African provenance of Nyasasaurus supports a southern Pangaean origin for Dinosauria.

Dr. Farish Jenkins 1940-2012

Many of you are already aware, but Professor Farish Jenkins of Harvard University passed away earlier this month at the age of 72. A vertebrate paleontologist, Dr. Jenkins was well known for his Triassic work in Greenland and even more so for his work in the Triassic and Jurassic of the Colorado Plateau, especially regarding early mammals.

http://www.nytimes.com/2012/12/01/us/farish-jenkins-fossils-expert-dies-at-72.html

Biomechanical Comments about Triassic Dinosaurs from Brazil

Delcourt, R., de Azevedo, S. A. K., Grillo, O. N., and F. O. Deantoni. 2012. Biomechanical comments about Triassic dinosaurs from Brazil. Papáis Avulsos de Zoologia 52:341-347.
 Abstract - Triassic dinosaurs of Brazil are found in Santa Maria and Caturrita formations, Rio Grande do Sul state, Brazil. There are three species known from the Santa Maria Formation (Staurikosaurus pricei, Saturnalia tupiniquim and Pampadromaeus barberenai), and two from Caturrita Formation (Guaibasaurus candelariensis and Unaysaurus tolentinoi). These dinosaur materials are, for the most part, well preserved and allow for descriptions of musculature and biomechanical studies. The lateral rotation of the Saturnalia femur is corroborated through calculations of muscle moment arms. The enhanced supracetabular crest of Saturnalia, Guaibasaurus, Staurikosaurus, Herrerasaurus ischigualastensis, Efraasia minor and Chormogisaurus [sic] novasi suggests that basal dinosaurs may have maintained an inclination of the trunk at least 20° on the horizontal axis. The pectoral girdle articulation of basal sauropodomorphs (Saturnalia and Unaysaurus) was established using a new method, the Clavicular Ring, and the scapular blade remains near 60° on the horizontal axis. This is a plesiomorphic condition among sauropodomorphs and is also seen in the articulated plateosauridae Seitaad ruessi. The Brazilian basal dinosaurs were lightweight with a body mass estimated around 18.5 kg for Staurikosaurus, 6.5 kg for Saturnalia, and 17 kg for Guaibasaurus. Pampadromaeus probably weighed 2.5 kg, but measures of its femur are necessary to confirm this hypothesis. The Triassic dinosaurs from Brazil were diversified but shared some functional aspects that were important in an evolutionary context.

Postcranial Anatomy of a Late Triassic Sauropodomorph from Argentina

Apaldetti, C., Diego Pol, D.,  and A. Yates. 2012. The postcranial anatomy of Coloradisaurus brevis (Dinosauria: Sauropodomorpha) from the Late Triassic of Argentina and its phylogenetic implications. Palaeontology (Early View) DOI: 10.1111/j.1475-4983.2012.01198.x

Abstract - Basal sauropodomorphs from the Upper Triassic Los Colorados Formation
 of north-western Argentina have been known for several decades but
 most of them are only briefly described. New postrcanial remains of
Coloradisaurus brevis, the most gracile sauropodomorph from this unit,
are described here and evaluated within a phylogenetic context. These
materials belong to a single individual and include elements of the
vertebral column, pectoral girdle, incomplete forelimb, pelvis and
hindlimb. These elements share an autapomorphic feature with the type
specimen of Coloradisaurus brevis and provide novel and unique
features that diagnose this taxon, such as pubic apron with
semicircular cross-section and with a depression on its anterior
surface, distal surface of the tibia deflected and facing
posterodistally and well-developed pyramidal dorsal process of the
posteromedial corner of the astragalus. Several postcranial characters
of Coloradisaurus are exclusively shared with Lufengosaurus, from the
Lower Jurassic of China. The inclusion of this information in two
recent phylogenetic data sets depicts Coloradisaurus as closely
related to Lufengosaurus and well nested within Plateosauria. Both
data sets used indicate strong character support for the inclusion of
Coloradisaurus and Lufengosaurus within Massospondylidae.

New Data on Small Theropod Footprints from Massachusetts

Dalman. S. G. 2012. New Data on Small Theropod Footprints from the Early Jurassic (Hettangian) Hartford Basin of Massachusetts, United States. Bulletin of the Peabody Museum of Natural History 53:333-353. doi:http://www.bioone.org/doi/abs/10.3374/014.053.0201

Abstract - A Portland Formation Lower Jurassic (Hettangian) dinosaur tracksite in Granby, Massachusetts, USA, has yielded a diverse dinosaur footprint assemblage. The tracksite preserves 140 theropod dinosaur footprints, ranging in length from 15 to 35 cm; the ichnofauna includes Anchisauripus, Eubrontes, Grallator and other extremely small theropod dinosaur footprints. The small tracks are compared with similar ichnites from the Lower Jurassic of western North America and central Poland. The small theropod footprints, which are described in detail, show some resemblance to the poorly known ichnogenus Stenonyx (Lull, 1904), which is considered an invalid ichnotaxon by many other workers. The footprints exhibit a distinct morphology of the metatarsophalangeal area, suggesting that these small ichnites are closely related to Kayentapus and Grallator. These small tracks are the first reported from the Hartford Basin of Granby, Massachusetts.

More on the Taxonomic Affinities of Isolated Leaf-Shaped Teeth from the Triassic

In the conclusions section of the recent paper by Kammerer et al., there is a worthwhile discussion regarding the taxonomic assignment of isolated Triassic teeth.  In the past some isolated leaf-shaped, denticulated teeth were considered apomorphic and used to erect discrete ornithischian dinosaur taxa (e.g., Hunt and Lucas, 1994; Heckert, 2004). Parker et al. (2005) argued that at least in Revueltosaurus callenderi, the teeth were apomorphic allowing assignment of non-dental material to the taxon. Irmis et al. (2007) discussed this in more detail, arguing the teeth of other purported ornithischians were not assignable to dinosaurs based solely on morphology and in fact could not be assigned to a more inclusive taxonomic level than Archosauromorpha.

However, in this recent paper Kammerer et al. note that many of these Triassic tooth taxa are very similar to the teeth of the traversodontid cynodonts Dadadon isaloi and Arctotraversodon plemmyridon. They especially note that the lower incisors of D. isaloi are very similar to the holotype teeth of Tecovasaurus murryi and the fourth upper incisor of D. isaloi has a similar morphology to Lucianosaurus wildi. Thus the characters that have been used to diagnose at least several of these 'tooth taxa' converge on other forms and are not autapomorphic. Although it would be tempting to use the teeth of Tecovasaurus and Lucianosaurus to suggest the further presence of cynodonts in the Triassic of the American southwest, we cannot discount the similarities of these teeth to archosaurian forms as well and therefore as noted by Kammerer et al., these isolated teeth can presently only be assigned to the level of Amniota  rather than Archosauriformes.

REFERENCES

Heckert, A.B. 2004. Late Triassic microvertebrates from the lower Chinle Group (Otischalkian-Adamanian: Carnian), southwestern U. S. A. New Mexico Museum of Natural History and Science Bulletin 27:1-170.

Hunt, A. P., and S.G. Lucas. 1994. Ornithischian dinosaurs from the Upper Triassic of the United States. pp. 227–241 in In the Shadows of the Dinosaurs: Early Mesozoic Tetrapods (ed. N. C. Fraser & H.-D. Sues). Cambridge University Press.
Irmis, R. B., Parker, W. G., Nesbitt, S. J., and J. Liu. 2007. Early ornithischian dinosaurs: the Triassic record. Historical Biology 19:3-22.

Kammerer, C. F., Flynn, J. J., Ranivoharimanana, L., and A. R. Wyss. 2012. Ontogeny in the Malagasy traversodontid Dadadon isaloi and a reconsideration of its phylogenetic relationships. Fieldiana Life and Earth Sciences 5:112-125.

Parker, W.G., Irmis, R.B., Nesbitt, S.J., Martz, J.W., and L.S. Browne. 2005. The Late Triassic pseudosuchian Revueltosaurus callenderi and its implications for the diversity of early ornithischian dinosaurs. Proceedings of the Royal Society B 272:963-969.
 

 

Ontogeny of the Malagasy Traversodontid Dadadon isaloi

Kammerer, C. F., Flynn, J. J., Ranivoharimanana, L., and A. R. Wyss. 2012. Ontogeny in the Malagasy Traversodontid Dadadon isaloi and a Reconsideration of its Phylogenetic Relationships. Fieldiana Life and Earth Sciences 5:112-125. doi: http://www.bioone.org/doi/abs/10.3158/2158-5520-5.1.112

Abstract - New craniodental material of the traversodontid Dadadon isaloi from Middle/Upper Triassic basal “Isalo II” beds of southwestern Madagascar is described. These specimens reveal several new autapomorphies of Dadadon, including paired foramina on the frontal near the anterior border of the postorbital and lower incisors with denticulated distal margins. The new material covers a broad size range, providing the first information on ontogeny in Dadadon. Larger (presumably older) specimens of Dadadon isaloi have more postcanine teeth, relatively longer, narrower snouts, and a higher degree of cranial ornamentation than smaller specimens. Postcanine replacement in Dadadon was similar to that of other traversodontids: new teeth erupted at the posterior end of the postcanine tooth row and moved forward. Using information from the new specimens, the position of Dadadon was tested in a new phylogenetic analysis of traversodontids. In the new analysis, Dadadon is strongly supported as a member of a clade also including the South American taxa Massetognathus and Santacruzodon, here named Massetognathinae subfam. nov. This clade is diagnosed by the presence of denticulated lower incisors, relatively small canines, three cusps in the labial margin of the upper postcanines, and low, flat skulls. Massetognathinae is the sister-group of Gomphodontosuchinae, which includes Gomphodontosuchus, Menadon, Protuberum, Exaeretodon, and Scalenodontoides. The Laurasian traversodontids (Arctotraversodon, Boreogomphodon, and Nanogomphodon) form a clade that is the sister-taxon of Massetognathinae + Gomphodontosuchinae. Denticulated incisors evolved multiple times in traversodontid evolution (in massetognathines and Arctotraversodon), and thus this group represents another possibility (besides various archosauromorphs) to be considered when attempting to identify isolated Triassic teeth with denticulated carinae lacking cingula.

Biomechanical Analysis of Triassic Cynodonts from Madagascar

Ranivoharimanana, L. 2012. Analyse biomécanique masticatrice chez des traversodontidés eucynodontes du Trias de Madagascar. [Biomechanical analysis of the jaw apparatus in eucynodont traversodontids from the Triassic of Madagascar]. Geodiversitas 34: 505–515.

Abstract - Mandible biomechanics analysis cannot take place without the understanding of the development degree and the arrangement pattern of the adductor muscles. In the non mammalian cynodonts, the temporal and the superficial masseter muscles play a primordial role in the lower jaw motion during the food processing. They constitute the key elements of this analysis. Previous studies on non mammalian cynodonts including Dadadon isaloi Flynn, Parrish, Rakotosamimanana, Simpson & Wyss, 1999 and Menadon besairiei Flynn, Parrish, Rakotosamimanana, Simpson & Wyss, 1999 demonstrated the realization, by these animals, of a complex dynamic occlusion of the lower and superior postcanine teeth. The consideration of the bite point as second occlusal fulcrum equal in status to the cranio-mandibular joint is the basis of the bifulcral model. This methodology allows: 1) to quantify the resistance opposed by food at the level of the occlusal site; and 2) to highlight a positive net vertical load, of compressive nature, acting to the level of the cranio-mandibular joint during the interactivity of the elevator muscles, i.e. during mastication.
 
RÉSUMÉ - L'analyse de la biomécanique de la mandibule ne peut s'effectuer sans la compréhension du degré de développement et du type d'arrangement des muscles adducteurs. Chez les cynodontes non mammaliens, le muscle temporal et le masséter superficiel jouent un rôle primordial dans les mouvements de la mâchoire inférieure lors de la transformation alimentaire. Ils constituent ainsi les éléments clés de cette analyse. Des études antérieures sur des cynodontes non mammaliens dont Dadadon isaloi Flynn, Parrish, Rakotosamimanana, Simpson & Wyss, 1999 et Menadon besairiei Flynn, Parrish, Rakotosamimanana, Simpson & Wyss, 1999, ont démontré la réalisation, par ces animaux, d'une occlusion dynamique complexe des dents postcanines, inférieures et supérieures. La considération du point de morsure comme second point d'appui au même titre que l'articulation crânio-mandibulaire est le fondement même du système à double leviers. Cette méthodologie a permis de: 1) quantifier la résistance opposée par la nourriture au niveau du site occlusal; et 2) mettre en évidence l'existence d'une charge verticale nette positive, de nature compressive agissant au niveau de l'articulation crânio-mandibulaire chez Dadadon isaloi et Menadon besairiei durant l'interactivité des muscles élévateurs au cours de la mastication.

Early Triassic Ichnoassemblages of Wyoming

This new paper suggests the presence of dinosauromorph (cf. Rotodactylus) and turtle-like (cf. Chelonipus) trackmakers from the Lower Triassic of Wyoming.

Lovelace, D. M., and S. D. Lovelace. 2012. Paleoenvironments and paleoecology of a Lower Triassic invertebrate and vertebrate ichnoassemblage from the Red Peak Formation (Chugwater Group), central Wyoming. Palaios 27:636-657. doi: 10.2110/​palo.2012.p12-011r

Abstract - The Lower Triassic Red Peak Formation of the Chugwater Group has long been considered to have an extremely poor paleontological record, although the cause for the apparent dearth of fossils has yet to be been determined. During the course of fieldwork in central Wyoming numerous vertebrate and invertebrate ichnogenera (n ≥ 11) were observed. Vertebrate tracks and trackways representative of dinosauromorph, archosaur, lepidosaur, and testudinate trackmakers were found (cf. Rotodactylus, Chirotherium barthii, Rhynchosauroides, and cf. Chelonipus respectively). An invertebrate ichnoassemblage composed of at least 6 ichnogenera consistent with the Scoyenia ichnofacies were also found (e.g., Diplichnites, Lockeia, Fuersichnus communis, Palaeophycus striatus, cf. Scoyenia, and cf. Scolicia). The majority of these tracks and traces were found in the upper platy facies (upper 10–20 m of the Red Peak Formation), which is thought to be no younger than upper Spathian in age. Sedimentary structures, architectural elements, and lateral stratigraphic relationships support the interpretation of floodplain, fluvial, and lacustrine deposition for the upper platy facies in central Wyoming. The Red Peak Formation vertebrate and invertebrate ichnoassemblages, along with their associated depositional environments, are consistent with a fluviolacustrine (continental) setting comparable to those described from Lower to Middle Triassic strata with a Pangean distribution, including the Moenkopi Formation in the southwestern United States. This ichnoassemblage provides the first opportunity to observe paleoecological diversity and associated paleoenvironments within the Lower Triassic of the Chugwater Group.

New Triassic Animal Video Clips (Museum in a Minute) from the New Mexico Museum of Natural History and Science

The New Mexico Museum of Natural History and Science has released a bunch of short, one minute video clips on a variety of fossil animals. I've linked a few of the Triassic-themed ones below. I think this is a great idea.

Revueltosaurus



Coelophysis


What is a Metoposaur?

Numerous Triassic Presentation Abstracts from the Fourth Latinamerican Congress of Vertebrate Paleontology

A new issue of the South American journal Ameghiniana includes (starting on page 32) the set of published abstracts from the IV Congreso Latinamericano  de Paleontologia Vertebrados, which was held in San Juan Argentina in September of 2011.  There are numerous Triassic themed abstracts in here as there were sessions of basal archosaurs, early theropods, therapsids, as well as geological sessions. I gave two talks at the meeting, one on newly discovered cranial material of Poposaurus gracilis; the other on the stratigraphic position of the Placerias Quarry of Arizona, which contains the earliest known neotheropod dinosaur. A volume is currently in press containing many of the papers from the basl archosaurs session.

You can download the published abstract volume here:

http://www.ameghiniana.org.ar/index.php/ameghiniana

Once the page loads, click on the small text "PDF" in the lower right corner.

Footprints of Large Theropod Dinosaurs from the Late Triassic of Brazil

The Caturrita Formation may be younger than previously thought and there is a currently undiscovered large theropod in the latest Triassic of Brazil.

da Silva, R. C., Barboni, R., Dutra, T., Godoy, M. M., and R. B. Binotto. 2012. Footprints of large theropod dinosaurs and implications on the age of Triassic biotas from southern Brazil. Journal of South American Earth Sciences 39:16-23. http://dx.doi.org/10.1016/j.jsames.2012.06.017

Abstract - Dinosaur footprints found in an outcrop of the Caturrita Formation (Rio Grande do Sul State, Southern Brazil), associated with a diverse and well preserved record of fauna and flora, reopen the debate about its exclusive Triassic age. The studied footprints were identified as Eubrontes isp. and are interpreted as having been produced by large theropod dinosaurs. The morphological characteristics and dimensions of the footprints are more derived than those commonly found in the Carnian–Norian, and are more consistent with those found during the Rhaetian–Jurassic. The trackmaker does not correspond to any type of dinosaur yet known from Triassic rocks of Brazil. Recent studies with the paleofloristic content of this unit also support a more advanced Rhaetian or even Jurassic age for this unit.


A New Ctenosauriscid from Eastern Europe, Bystrowisuchus flerovi May Represent the Oldest Known Crown-Group Archosaur


This paper describes a new ctenosauriscid archosaur from the Early Triassic of EuropeBystrowisuchus flerovi is based upon a series of fragmentary cervical vertebrae and a partial right ilium. It differs from other ctenosauriscids in the presence of expanded spine tables on the apices of the neural spines, and by possessing generally shorter neural spines. Based on these characters Sennikov considers Bystrowisuchus to be transitional between rauisuchids and ctenosauriscids. Note that Sennikov prefers to use traditional Linnaean systematics rather than cladistics (and still recognizes Thecodontia as a taxonomic entity). A new family Lotosauridae is erected and considered distinct from other ctenosauriscids [Ctenosauriscidae]. The type locality is dated latest Olenekian, which means that Bystrowisuchus  is probably older than Xilousuchus which is ambiguously from the latest Olenekian-early Anisian of China and therefore could represent the oldest record of a ctenosauriscid and crown-group archosaur.

Sennikov, A. G. 2012. The first ctenosauriscid (Reptilia: Archosauromorpha) from the Lower Triassic of Eastern Europe. Paleontological Journal [Paleontologicheskii Zhurnal] 46:499-511.

Abstract - A new Early Triassic thecodont from the Donskaya Luka locality is described. A new species and genus of Rauisuchidae, Bystrowisuchus flerovi gen. et sp. nov., the first East European and earliest known member of the family Ctenosauriscidae is established. The taxonomy and phylogeny of Rauisuchidae and their stratigraphical and geographical distribution in connection with new finds are discussed.

A New Turtle Dominated Fossil Biota from the Late Triassic (Norian) of Poland


This paper documents a newly discovered fauna from the Norian of Poland that is important because it is dominated by fossils of what is most likely a new taxon of turtle. Of course Late Triassic terrestrial turtles are very rare so we will watch further research from this site with interest. The locality also includes other vertebrate taxa including a coelophysoid dinosaur and an aetosaur.  The aetosaur is of interest because the dorsal vertebra possesses a distinct hyposphene, a character previously only found in Desmatosuchus from North America and Aetobarbakinoides from Brazil.  This new site is also significant because it preserves micro and macrofloral fossils, which are generally uncommonly associated with vertebrate remains. Large temnospondyls are also rare in the Norian, but this site has one as well.

Sulej, T., Niedźwiedzki, G., and R. Bronowicz. 2012. A new Late Triassic vertebrate fauna from Poland with turtles, aetosaurs, and coelophysoid dinosaurs. Journal of Vertebrate Paleontology 23: 1033-1041. DOI:10.1080/02724634.2012.694384

Abstract - We report a new site with an occurrence of isolated bones of a Palaeochersis-like turtle in Norian-Rhaetian fluvial sediments from southern Poland. The turtle remains are associated with bones of a medium-sized aetosaur, a coelophysoid dinosaur, and a larger carnivorous archosaur, as well as a hybodontid shark, ganoid and dipnoan fishes, and a large temnospondyl.

You Don't Need to Purchase Articles for Outrageous Fees Anymore. You Can Now RENT Them Instead!

In putting together my last post I noticed something interesting (disturbing?) from the Cambridge Journals site.  If you would like to purchase a PDF of the Parringtonia gracilis redescription paper I just mentioned it will cost you $45.00 U.S. The atrociousness of this has been discussed in detail at several other blogs most notably by the SV-POW guys.  Anyhow, for those of you who don't want to (or can't afford to) shell out this kind of cash for a single article there is now another option available.  You can rent the article instead for the low(er) price of $5.99 U.S.!!!  You get 24 hour access to the article, which is probably enough to cram in a couple of readings if you don't really want to fully comprehend the paper. Also just think of the hard drive space you'll save if all of your PDFs 'disappeared' after a 24 hour period.  Currently I'm very hard pressed to think of a reason why this would be attractive. I suppose if you simply wanted to download the article and print it for future use.... Anyone else able to present this in a positive light?

Redescription of the Archosaur Parringtonia gracilis from the Middle Triassic Manda Beds of Tanzania


Here is another redescription of another of the enigmatic archosauriforms from the Middle Triassic Manda Formation. This study confirms the affinity of Parringtonia gracilis and Erpetosuchus granti, and reinforces the importance of redescribing these older taxa using an apomorphy-based approach and placing them in a modern phylogenetic analysis. Unfortunately the exact position of Erpetosuchidae with Archosauria was not able to be precisely determined.

Nesbitt, S. J., and R. J. Butler. 2012. Redescription of the archosaur Parringtonia gracilis from the Middle Triassic Manda beds of Tanzania, and the antiquity of Erpetosuchidae. Geological Magazine (FirstView article), 14p. doi:10.1017/S0016756812000362 

Abstract - Parringtonia gracilis Huene, 1939 is represented by both cranial and postcranial material collected from the lower Middle Triassic (Anisian) Lifua Member of the Manda beds in southwestern Tanzania. This aberrant taxon was previously proposed to have affinities with pseudosuchian archosaurs, and specifically with the enigmatic Erpetosuchus granti from the Upper Triassic of Scotland. Here, we confirm the close affinities of Parringtonia gracilis and Erpetosuchus granti based on the following unambiguous synapomorphies: mediolaterally expanded posterior portion of the maxilla, alveoli present only in the anterior half of the maxilla, and absence of tooth serrations. Furthermore, the two taxa share osteoderms with deep sculpturing, a deep fossa on the dorsal margin of the neural spines and a heavily waisted shaft of the scapula. We added both Parringtonia gracilis and Erpetosuchus granti into a comprehensive phylogenetic analysis of early archosaurs and found that these taxa are clearly referable to Archosauria but that relationships are poorly resolved at the base of this clade. However, our analysis demonstrates that Erpetosuchus granti is not closely related to Crocodylomorpha, as has been hypothesized previously. The Erpetosuchidae are a clade of small-bodied archosaurs that have a poor fossil record but have members from both northern and southern Pangaea, ranging temporally from the Middle to Late Triassic. Thus, Erpetosuchidae is part of the early archosaurian radiation.

Diandongos​uchus, A New Archosaur from Triassic of China

There are lots of incredible specimens coming out of the Middle Triassic in recent years (SVP attendees will see another in a talk this year by Sterling Nesbitt and colleagues), and this amazing fossil from the Ladinian of China does not disappoint. It consists of most of a partially articulated/associated skeleton found in marine sediments not far from where the early diverging poposauroid  Qianosuchus mixtus was  recovered some time ago.

The authors have provided color figures that allow the reader to see many of the details of the skeleton; however, the semi-articulated nature of the specimen seems to prelude dismantling of the specimen to see three dimensional views of the specimen. Furthermore, because it is in a marine shale, some crushing of the specimen has occurred. This is unfortunate because it does not allow clear study of the ilia or of the ends of the femora, which would provide key characters for the taxonomic placement of the specimen. Li et al. do code the specimen into Sterling Nesbitt's recent (2011) phylogenetic matrix of Archosauriformes and it is recovered, with much support, as the earliest diverging poposauroid. This is of interest of course because it suggests that the plesiomorphic conditions for poposauroids are quadrupedal, toothed, long-snouted forms that lack an expanded dorsal sail, possess osteoderms, and are possibly semi-aquatic. Compare this to other members of the clade such as Effigia okeeffae. The amount of morphological variation in this group is incredible.

I'll admit that I'm not entirely convinced of the phylogenetic placement of this specimen, but unfortunately I cannot get into the details of why at this time. Let's just say that this is an extremely interesting taxon that should be the subject of debate for a while to come. I do really wish the ilia were better preserved or more visible, but it is really hard to complain about such a beautiful fossil.

Li, C., Wu, X.-C., Zhao, L.-J., Sato, T. and L.-T. Wang. 2012. A new archosaur (Diapsida, Archosauriformes) from the marine Triassic of China. Journal of Vertebrate Paleontology 32(5): 1064-1081. DOI:10.1080/02724634.2012.694383http://www.tandfonline.com/doi/abs/10.1080/02724634.2012.694383

Abstract - A new Middle Triassic archosaur, Diandongosuchus fuyuanensis, gen. et
sp. nov., is described on the basis of a skeleton from the Zhuganpo Member (Ladinian) of the Falang Formation, eastern Yunnan Province, China. It is primarily characterized by the nasal process of the premaxilla extending posteriorly well beyond the external naris, the super-sized coracoid foramen laterally bordered by the scapula, the ischium with a strongly expanded medial portion anteroposteriorly longer than the proximodistal height of the bone, and anteriorly notched cervical osteoderms. D. fuyuanensis is a pseudosuchian on the basis of the crocodile-normal tarsal joint and other features, such as the distal end of the ulna in posterolateral view squared off, osteoderms with a distinct anterior process, the presacral vertebrae dorsally covered by more than one osteoderm, dorsal osteoderm alignment dorsal to presacrals 10–24 staggered, the pubis-ischium contact reduced to a thin proximal contact, and the medial contact of the ischia extensive but the dorsal margins separate. It is from a marine deposit but shows few morphological adaptations of the postcranial skeleton for a semiaquatic way of life when compared with Qianosuchus from the Anisian limestone of the same area. A phylogenetic analysis derived from an existing data matrix suggests that the new archosaur occupies the basal-most position in Poposauroidea and further confirms the poposauroid status of Qianosuchus. On the basis of current information, the discovery of Diandongosuchus does not firmly underscore the affinity of the semiterrestrial vertebrate faunas between the eastern and western regions along the northern coastline of the Tethys.

More Photos from the Petrified Forest

I'm currently creating a database of all of our photos from the last decade of paleontological work at Petrified Forest National Park and am working through 2002. These photos were taken by Daniel Woody who was investigating the Sonsela Member of the Chinle Formmation and assisting with the paleontology work. I'm amazed how far the quality of digital photos have over the decade!

Phytosaur lower jaw in the Crystal Forest

Phytosaur quadrate bone in the Blue Mesa Member

Triassic Fieldwork in Utah

Randall Irmis of the Utah Museum of Natural History is posting about current fieldwork in the Triassic of Utah.  You can check out the first post here and check back for more to follow.

Reevaluating the 'Prosauropods' of the Upper Triassic Caturrita Formation of Brazil


Bittencourt, J. S., Stock da Rosa, A. A., and M. C. Langer. in press. Dinosaur remains from the ‘Botucaraí Hill’ (Caturrita Formation), Late Triassic of south Brazil, and their stratigraphic context. Historical Biology. DOI:10.1080/08912963.2012.694881

Abstract - Vertebrate fossils recovered from sites nearby the Botucaraí Hill and Candelária (Caturrita Formation) depict a diverse Late Triassic tetrapod fauna from south Brazil. These records are of key importance to the biostratigraphy of the upper sections of the Rosario do Sul Group. A lithological and biostratigraphic survey on the main fossil localities of the Botucaraí Hill area confirms the occurrence of the lower Hyperodapedon and the upper Riograndia Assemblage Zones in the region, the latter yielding early saurischians. In this paper, three incomplete dinosaur specimens, an isolated sacral vertebra, an articulated left pubis–ischium and an isolated right ischium, from the ‘Botucaraí Hill’ site are described. A comparative survey suggests that these specimens have sauropodomorph affinities, but probably more primitive than typical ‘prosauropods’ from the Norian-Early Jurassic. Regardless of the phylogenetic position of Guaibasaurus as theropod or sauropodomorph, their occurrence in the Caturrita Formation, which also yielded ‘core prosauropods’ from the Santa Maria region, suggests either the survival of early members of the clade with more derived ‘prosauropods’ or that heterochronous faunas are sampled from that stratigraphic unit.

Examining the Effects of Dataset Quality on Paleodiversity Studies

I would love to do a similar study for the Chinle Formation...

Irmis, R. B., Whiteside, J. H., and C. F. Kammerer. In press.  Non-biotic controls of observed diversity in the paleontologic record: An example from the Permo-Triassic Karoo Basin of South Africa.  Palaeogeography, Palaeoclimatology, Palaeoecology.  doi: 10.1016/j.palaeo.2012.07.014.
 Abstract - Paleodiversity trends through geologic time can be affected by a number of geologic, taphonomic, and anthropogenic biases that obscure or prejudice paleoecological patterns in the fossil record. Although much work has concentrated on the relationship between geologic exposure, sample size, and taxonomic richness (i.e., number of taxa), few studies have investigated the potential effects of dataset quality and changing taxonomy. We use four different specimen-level datasets of Permo-Triassic tetrapods from the Karoo Basin of South Africa to investigate how sample size, geologic outcrop, dataset quality, and taxonomic revision all affect observed estimates of generic richness, evenness, and relative abundance. Our results indicate that large-scale patterns of richness, evenness, and abundance, such as the effects of the end-Permian mass extinction, are generally robust to these potential biases across the four different datasets. In contrast, absolute values vary significantly as do finer-scale patterns. In agreement with past studies, taxonomic errors, revised taxonomy, and new taxa have little effect on patterns of richness and evenness; instead, the addition of large numbers of new specimens to the dataset has the largest effect on these paleodiversity metrics, despite application of samplestandardization. We conclude that although large specimen datasets (hundreds to thousands of specimens) are robust to various potential biases, and can recover large-scale paleobiologic trends, they are still affected by many non-biotic controls, and workers should strive to improve dataset quality and understand the underlying reasons for observed paleodiversity patterns.

New Ladinian Biostratigraphic Correlation Between South America and South Africa

Nice biostratigraphic correlation between the Santa Maria Formation of Brazil and the Karoo of South Africa. Partially fills the 'Ladinian Gap' in the Karoo.

Abdala, F., Marsicano, C. A., Smith, R. M. H., and R. Swart. 2012. Strengthening western Gondwanan correlations: a Brazilian dicynodont (Synapsida, Anomodontia) in the Middle Triassic of Namibia. Gondwana Research (advance online publication)
http://dx.doi.org/10.1016/j.gr.2012.07.011

Abstract - Terrestrial Middle Triassic strata occur throughout continental Africa, and are particularly well exposed in South Africa, Tanzania, Zambia, and Namibia. The youngest age for all these African deposits is widely accepted as early Middle Triassic (Anisian). Fossils collected recently from the uppermost strata of the upper Omingonde Formation in Namibia highlighted the presence of Chiniquodon, a carnivorous cynodont previously only found in Ladinian-Carnian aged rocks of South America. In addition, work in progress indicates that a large archosaur, originally reported as Erythrosuchus, also discovered from levels close to the top of this unit, is in fact a rauisuchian, a group of archosaurs well known from Ladinian-Carnian beds of southern South America. Here we present the first record of the tuskless dicynodont Stahleckeria potens, from the top of the upper Omingonde Formation in central Namibia. This taxon was up until now only known from the Ladinian Dinodontosaurus Assemblage Zone of the Santa Maria Formation in southern Brazil. Thus, compelling evidence for a Ladinian age for the upper levels of the upper Omingonde Formation is provided by two therapsid and one archosaur taxa. The tetrapod fauna of the upper Omingonde Formation partially fills the gap of the well-documented hiatus (Ladinian gap), prevalent throughout the Karoo basins of south and central Africa. The presence of the same therapsid taxa in the Namibian Waterberg Basin and the Paraná Basin of Brazil during Middle Triassic suggests that these basins were biogeographically linked through a series of interconnecting lowlands, with no major ecological, climatic and/or physical barriers.

New ICS International Chronostratigraphy Chart Uses the Long Norian

The base of the Norian stage is set at ~228 Ma on the new chronstratigraphy chart of the International Commission on Stratigraphy.  Still needs further support and eventially a golden spike, but this is the first time the ICS has used the long Norian hypothesis on its published chart.

You can download the latest timescale from here:

http://www.stratigraphy.org/ics%20chart/ChronostratChart2012.pdf

First Record of Late Triassic Vertebrate Fossils from Lithuania and the Paleobiogeography of Phytosaurs


Brusatte, S. L., Butler, R. J., Niedźwiedzki, G., Sulej, T., Bronowicz, R., and J. Satkūnas. 2012. First record of Mesozoic terrestrial vertebrates from Lithuania: phytosaurs (Diapsida: Archosauriformes) of probable Late Triassic age, with a review of phytosaur biogeography. Geological Magazine (early online) 13 pp. doi:10.1017/S0016756812000428


Abstract – Fossils of Mesozoic terrestrial vertebrates from Lithuania and the wider East Baltic region
of Europe have previously been unknown.We here report the first Mesozoic terrestrial vertebrate fossils
from Lithuania: two premaxillary specimens and three teeth that belong to Phytosauria, a common
clade of semiaquatic Triassic archosauriforms. These specimens represent an uncrested phytosaur,
similar to several species within the genera Paleorhinus, Parasuchus, Rutiodon and Nicrosaurus.
Because phytosaurs are currently only known from the Upper Triassic, their discovery in northwestern
Lithuania (the Šaltiškiai clay-pit) suggests that at least part of the Triassic succession in this region
is Late Triassic in age, and is not solely Early Triassic as has been previously considered. The new
specimens are among the most northerly occurrences of phytosaurs in the Late Triassic, as Lithuania
was approximately 7–10◦ further north than classic phytosaur-bearing localities in nearby Germany and
Poland, and as much as 40◦ further north than the best-sampled phytosaur localities in North America.
The far northerly occurrence of the Lithuanian fossils prompts a review of phytosaur biogeography
and distribution, which suggests that these predators were widely distributed in the Triassic monsoonal
belt but rarer in more arid regions.

Reanalysis of the Archosauriform Proterochampsa from the Late Triassic of Argentina

Dilkes, D., and A. Arcucci. 2012. Proterochampsa barrionuevoi (Archosauriformes: Proterochampsia) from The Late Triassic (Carnian) of Argentina and a phylogenetic analysis of Proterochampsia. Palaeontology early online. doi: 10.1111/j.1475-4983.2012.01170.x   http://onlinelibrary.wiley.com/doi/10.1111/j.1475-4983.2012.01170.x/abstract

Abstract - Restudy of skulls and available postcrania of the proterochampsian archosauriform Proterochampsa barrionuevoi from the Ischigualasto Formation (Upper Triassic, Carnian) in the San Juan Province, Argentina, confirms that the genus is diagnosed by autapomorphies that include dermal sculpturing consisting of prominent ridges and nodular protuberances, a large hook-like lateral projection on the quadratojugal, an antorbital fossa restricted to a depression along the maxilla, lateral expansion of the premaxilla anterior to the premaxilla–maxilla contact, absence of a supratemporal fossa, exclusion of jugal from suborbital fenestra, basal tubera of parabasisphenoid facing ventrally and reaching laterally beyond the basipterygoid process, and a ventral lamina on the angular. Proterochampsa nodosa is a valid species distinguished from P. barrionuevoi by fewer cranial ridges with larger protuberances, relatively smaller supratemporal fenestrae and width of frontals between orbits less than that of the nasals. A phylogenetic analysis supports the monophyly of Proterochampsia consisting of Proterochampsa, Chanaresuchus bonapartei, Gualosuchus reigi, Tropidosuchus romeri and Cerritosaurus binsfeldi. A temporal separation between the two basal proterochampsians with earliest records in the Late Triassic (Proterochampsa and Cerritosaurus) and Chanaresuchus, Gualosuchus and Tropidosuchus in the Middle Triassic indicates hidden proterochampsian diversity in the Middle Triassic.

Associated Evolution Of Bipedality And Cursoriality Among Triassic Archosaurs

Kubo, T., and M. O. Kubo. 2012. Associated evolution of bipedality and cursoriality among Triassic archosaurs: a phylogenetically controlled evaluation. Paleobiology 38: 474–485. http://www.bioone.org/doi/full/10.1666/11015.1
Abstract - Bipedalism evolved more than twice among archosaurs, and it is a characteristic of basal dinosaurs and a prerequisite for avian flight. Nevertheless, the reasons for the evolution of bipedalism among archosaurs have barely been investigated. Comparative analysis using phylogenetically independent contrasts showed a significant correlation between bipedality (relative length of forelimb) and cursoriality (relative length of metatarsal III) among Triassic archosaurs. This result indicates that, among Triassic archosaurs, bipeds could run faster than quadrupeds. Bipedalism is probably an adaptation for cursoriality among archosaurs, which may explain why bipedalism evolved convergently in the crocodilian and bird lineages. This result also indicates that the means of acquiring cursoriality may differ between archosaurs and mammals.

As "Leisurely" Divers, Triassic Ichthyosaurs Did Not Suffer From "The Bends"

Rothschild, B. M., Xiaoting, Z., and L. D. Martin. 2012. Adaptations for marine habitat and the effect of Triassic and Jurassic predator pressure on development of decompression syndrome in ichthyosaurs. Naturwissenschaften 99:443–448 DOI 10.1007/s00114-012-0918-0
Abstract - Decompression syndrome (caisson disease or the the bends) resulting in avascular necrosis has been documented in mosasaurs, sauropterygians, ichthyosaurs, and turtles from the Middle Jurassic to Late Cretaceous, but it was unclear that this disease occurred as far back as the Triassic. We have examined a large Triassic sample of ichthyosaurs and compared it with an equally large post- Triassic sample. Avascular necrosis was observed in over 15%of LateMiddle Jurassic to Cretaceous ichthyosaurs with the highest occurrence (18 %) in the Early Cretaceous, but was rare or absent in geologically older specimens. Triassic reptiles that dive were either physiologically protected, or rapid changes of their position in the water column rare and insignificant enough to prevent being recorded in the skeleton. Emergency surfacing due to a threat from an underwater predator may be the most important cause of avascular necrosis for air-breathing divers, with relative frequency of such events documented in the skeleton. Diving in the Triassic appears to have been a leisurelybehavior until the evolution of large predators in the Late Jurassic that forced sudden depth alterations contributed to a higher occurrence of bends.

New U-Pb Dates for the Middle Triassic of Monte San Giorgio

Stockar, R., Baumgartner, P. O., and D. Condon. 2012. Integrated Ladinian bio-chronostratigraphy and geochrononology of Monte San Giorgio (Southern Alps, Switzerland). Swiss Journal of Geosciences 105:85-108.
Abstract - New biostratigraphic data significantly improve the age assignment of the Ladinian succession of Monte San Giorgio (UNESCO World Heritage List site, Southern Alps, Switzerland), whose world-famous fossil marine vertebrate faunas are now dated to the substage and zone levels. High-resolution single-zircon U–Pb dating was performed using ID-TIMS and chemical abrasion (CA) pre-treatment technique on volcanic ash layers intercalated in the biostratigraphically-defined intervals of the Meride Limestone. It yielded ages of 241.07 ± 0.13 Ma (Cava superiore beds, P. gredleri Zone), 240.63 ± 0.13 Ma (Cassina beds, P gredleri/P. archelaus transition Zone) and 239.51 ± 0.15 Ma (Lower Kalkschieferzone, P. archelaus Zone). Our results suggest that the time interval including the vertebrate-bearing Middle Triassic section spans around 4 Myr and is thus significantly shorter than so far assumed. The San Giorgio Dolomite and the Meride Limestone correlate with intervals of the Buchenstein Formation and the Wengen Formation in the reference section at Bagolino, where the Global boundary Stratotype Section and Point (GSSP) for the base of the Ladinian was defined. The new radio-isotopic ages of the Meride Limestone are up to 2 Myr older than those published for the biostratigraphically-equivalent intervals at Bagolino but they are consistent with the recent re-dating of the underlying Besano Formation, also performed using the CA technique. Average sedimentation rates at Monte San Giorgio are by more than an order of magnitude higher compared to those assumed for the Buchenstein Formation, which formed under sediment starved pelagic conditions, and reflect prevailing high subsidence and high carbonate mud supply from the adjoining Salvatore/Esino platforms.  Finally, the high-resolution U–Pb ages allow a correlation of the vertebrate faunas of the Cava superiore/Cava inferior beds with the marine vertebrate record of the Prosanto Formation (Upper Austroalpine), so far precluded by the poor biostratigraphic control of the latter.

First Procolophonid from the Lower Triassic of Madagascar

Falconnet, J., Andriamihaja, M., Läng, É.,  and J.-S. Steyer. 2012. First procolophonid (Reptilia, Parareptilia) from the Lower Triassic of Madagascar. Comptes Rendus Palevol (advance online publication) http://dx.doi.org/10.1016/j.crpv.2012.04.001
Abstract - Lasasaurus beltanae nov. gen. nov. sp., a new procolophonid (Reptilia, Parareptilia) from the Lower Triassic of Madagascar, is represented by a single partial skeleton preserved in a ferro-calcareous nodule from the Middle Sakamena Formation, in the North of the island. This new taxon is unique in possessing peculiar, fine and dendritic crests running along the posterolateral side of the squamosal, widely spaced maxillary teeth, subparallel mesiodistal ridges connecting maxillary teeth to the tooth row, and a strongly acute anterior margin of the copula (hyoid bone). This well-preserved specimen belongs to a juvenile individual. The inclusion of L. beltanae nov. gen. nov. sp. in a phylogenetic analysis suggests that it is close to Theledectinae, Procolophoninae, and Leptopleurinae, though their respective relationships are uncertain. This specimen is the first procolophonid described from Madagascar and represents a minor terrestrial component of a coastal vertebrate assemblage dominated by amphibious to fully-aquatic taxa.

Two New Triassic Archosaurian Taxa in the New Issue of Acta Palaeontologica Polonica

These two papers have been available for awhile as accepted manuscripts, but now they are officially out and freely downloadable.

Niedźwiedzki, G., Sulej, T., and J. Dzik. 2012. A large predatory archosaur from the Late Triassic of Poland. Acta Palaeontologica Polonica 57 (2): 267-276. doi: http://dx.doi.org/10.4202/app.2010.0045

Abstract - We describe a new large predatory archosaur, Smok wawelski gen. et sp. nov., from the latest Triassic (latest Norian–early Rhaetian; approximately 205–200 Ma) of Lisowice (Lipie Śląskie clay−pit) in southern Poland. The length of the reconstructed skeleton is 5–6 m and that of the skull 50–60 cm, making S. wawelski larger than any other known predatory archosaur from the Late Triassic and Early Jurassic of central Europe (including theropod dinosaurs and “rauisuchian” crurotarsans). The holotype braincase is associated with skull, pelvic and isolated limb−bones found in close proximity (within 30 m), and we regard them as belonging to the same individual. Large, apparently tridactyl tracks that occur in the same rock unit may have been left by animals of the same species. The highly autapomorphic braincase shows large attachment areas for hypertrophied protractor pterygoideus muscles on the lateral surface and a wide, funnel−like region between the basal tubera and basipterygoid processes on the ventral surface. The skeleton (cranial and postcranial) possesses some features similar to those in theropod dinosaurs and others to those in large crocodile−line archosaurs (“rauisuchians”), rendering phylogenetic placement of S. wawelski difficult at this time.

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Kammerer, C. F., Nesbitt, S. J., and N. H. Shubin. 2012. The first silesaurid dinosauriform from the Late Triassic of Morocco. Acta Palaeontologica Polonica 57 (2): 277-284 doi: http://dx.doi.org/10.4202/app.2011.0015

Abstract - Disarticulated material from the Late Triassic Timezgadiouine Formation in the Argana Basin of Morocco represents a new taxon of silesaurid dinosauromorph, Diodorus scytobrachion gen. et sp. nov. D. scytobrachion can be distinguished from other silesaurids by the presence of anteriorly−canted teeth that decrease in size towards the anterior end of the dentary and a distinct lateral ridge running parallel to the dentary alveolar margin. In a phylogenetic analysis, D. scytobrachion is recovered as the sister−taxon to the Brazilian Sacisaurus agudoensis, nested deep within Silesauridae. This new taxon provides further evidence of a near−cosmopolitan range for basal dinosauriforms in the Late Triassic and further demonstrates the disparity of dental morphologies within Silesauridae.

New Triassic Papers

Thanks to Ben Creisler for originally compiling these...

Chen, Z. Q-., and M. J. Benton. 2012. The timing and pattern of biotic recovery following the end-Permian mass extinction. Nature Geoscience 5: 375–383doi:10.1038/ngeo1475
Abstract - The aftermath of the great end-Permian period mass extinction 252 Myr ago shows how life can recover from the loss of >90% species globally. The crisis was triggered by a number of physical environmental shocks (global warming, acid rain, ocean acidification and ocean anoxia), and some of these were repeated over the next 5–6 Myr. Ammonoids and some other groups diversified rapidly, within 1–3 Myr, but extinctions continued through the Early Triassic period. Triassic ecosystems were rebuilt stepwise from low to high trophic levels through the Early to Middle Triassic, and a stable, complex ecosystem did not re-emerge until the beginning of the Middle Triassic, 8–9 Myr after the crisis. A positive aspect of the recovery was the emergence of entirely new groups, such as marine reptiles and decapod crustaceans, as well as new tetrapods on land, including — eventually — dinosaurs. The stepwise recovery of life in the Triassic could have been delayed either by biotic drivers (complex multispecies interactions) or physical perturbations, or a combination of both. This is an example of the wider debate about the relative roles of intrinsic and extrinsic drivers of large-scale evolution.


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Lindström, S., van de Schootbrugge, B., Dybkjær, K., Pedersen, G. K.,  Fiebig, J., Nielsen, L. H.,  and S. Richoz. 2012.  No causal link between terrestrial ecosystem change and methane release during the end-Triassic mass extinction.
Geology 40(6): 531-534
doi: 10.1130/G32928.1

Abstract - Profound changes in both marine and terrestrial biota during the end-Triassic mass extinction event and associated successive carbon cycle perturbations across the Triassic-Jurassic boundary (T-J, 201.3 Ma) have primarily been attributed to volcanic emissions from the Central Atlantic Magmatic Province and/or injection of methane. Here we present a new extended organic carbon isotope record from a cored T-J boundary succession in the Danish Basin, dated by high-resolution palynostratigraphy and supplemented by a marine faunal record. Correlated with reference C-isotope and biotic records from the UK, it provides new evidence that the major biotic changes, both on land and in the oceans, commenced prior to the most prominent negative C-isotope excursion. If massive methane release was involved, it did not trigger the end-Triassic mass extinction. Instead, this negative C-isotope excursion is contemporaneous with the onset of floral recovery on land, whereas marine ecosystems remained perturbed. The decoupling between ecosystem recovery on land and in the sea is more likely explained by long-term flood basalt volcanism releasing both SO2 and CO2 with short- and long-term effects, respectively.

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Hamad, A. M. B. A. Jasper, A., and D. Uhl. 2012. The record of Triassic charcoal and other evidence for palaeo-wildfires: Signal for atmospheric oxygen levels, taphonomic biases or lack of fuel? International Journal of Coal Geology  96–97: 60–71 http://dx.doi.org/10.1016/j.coal.2012.03.006
Abstract - As wildfires are today important sources of disturbance in many terrestrial ecosystems, it is of great interest to understand how different environmental parameters and fire-activity interacted during past periods of the Earth history. Fossil charcoal, inertinites, and pyrogenic polycyclic aromatic hydrocarbons (PAHs) represent the only direct evidence for the occurrence of such palaeo-wildfires. In the present study, a review of published data, together with new data on the occurrence of fossil charcoal for the Permian and the Triassic is presented. For a long time, it has been speculated, that an assumed lack of evidence for palaeo-wildfires during the Triassic should be explained by a large drop in atmospheric oxygen concentration following or during the end-Permian mass extinction event, preventing the occurrence of wildfires. However, evidence for palaeo-wildfires is relatively common in many middle and late Triassic strata, whereas such evidence is almost totally lacking from early Triassic sediments. The interpretation of this “charcoal gap” or depression is difficult, as many factors (e.g. atmospheric oxygen concentration, taphonomical biases, lack of sediments suitable for the preservation of macroscopic charcoal, lack of fuel, and “ignorance” of scientists) may have influenced not only the production, but also the preservation and recovery of evidence for palaeo-wildfires during this period. Thus, it is not clear whether this Early Triassic “charcoal gap” can also be seen as evidence for an assumed “wildfire gap” or not. Without any doubt further investigations on the early Triassic record of charcoal and other evidence for palaeo-wildfires will be necessary before this problem can be solved. In fact, it can be expected that the number of published records of (early) Triassic evidence for palaeo-wildfires will increase in the future as more and more scientist working on
sediments of this age may become aware of the interest in fires from this time. This will certainly make it possible to give a much better picture of the temporal and regional distribution of wildfires during this period in the future.


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Bodzioch, A., and M. Kowal-Linka. 2012. Unraveling the origin of the Late Triassic multitaxic bone accumulation at Krasiejów (S Poland) by diagenetic analysis. Palaeogeography, Palaeoclimatology, Palaeoecology (advance online publication) http://dx.doi.org/10.1016/j.palaeo.2012.05.015

Abstract - A study of aquatic and terrestrial vertebrate remains from a bonebed in the Late Triassic continental succession near Krasiejów (S Poland) shows it was deposited by a single catastrophic event, perhaps a flood. Hardparts of Metoposaurus, Paleorhinus, and Stagonolepis show sedimentary infill and geochemical evidence for early diagenesis at different times and in different microenvironments. The infills in the aquatic animal bones (sediment, pyrite, calcite) show deposition in a freshwater environment, while those in the terrestrial Stagonolepis remains (mainly barite) point to an arid terrestial environment. The trace element content of the remains, together with the absence of a distinct pattern of element distribution, supports the conclusion that individual hardparts underwent diagenesis in various microenvironments and at different times. The accumulation of multitaxic vertebrate remains in a single bed clearly indicates event deposition. The hardparts must originally have been deposited at various locations during different times, but were later transported and deposited together in a pond by a short-lived, high-energy event, probably a flood after catastrophic rainfall.

Skull Mechanics of Capitosaurs (Amphibia: Temnospondyli)

Fortuny, J., Marcé-Nogué, J., Gil, L. and Galobart, À. 2012. Skull Mechanics and the Evolutionary Patterns of the Otic Notch Closure in Capitosaurs (Amphibia: Temnospondyli). The Anatomical Record (advance online publication) doi: 10.1002/ar.22486 http://onlinelibrary.wiley.com/doi/10.1002/ar.22486/abstract

Abstract - Capitosaurs were among the largest amphibians that have ever lived. Their members displayed an amphibious lifestyle. We provide new information on functional morphology data, using finite element analysis (FEA) which has palaeoecological implications for the group. Our analyses included 17 taxa using (2D) plate models to test four loading cases (bilateral, unilateral and lateral bitings and skull raising system simulation). Our results demonstrates that, when feeding, capitosaurs concentrated the stress at the circumorbital region of the capitosaur skull and cranial sutures probably played a key role in dissipating and absorbing the stress generated during biting. Basal members (as Wetlugasaurus) were probably less specialized forms, while during Middle- and Late Triassic the group radiated into different ecomorphotypes with closed otic notch forms (as Cyclotosaurus) resulting in the strongest skulls during biting. Previous interpretations discussed a trend from an open to closed otic notch associated with lateral repositioning of the tabular horns, but the analysis of the skull-raising system reveals that taxa exhibiting posteriorly directed tabular horns display similar results during skull raising to those of closed otic notch taxa. Our results suggest that various constraints besides otic notch morphology, such as the elongation of the tabular horns, snout length, skull width and position, and size of the orbits affect the function of the skull. On the light of our results, capitosaur skull showed a trend to reduce the stresses and deformation during biting. Capitosaurs could be considered crocodilian analogues as they were top-level predators in fluvial and brackish Triassic ecosystems.

A New Neocalamites from the Upper Triassic of China

Zan, S.-Q., Axsmith, B. J, Escapa, I., Fraser, N. C., Liu, F.-X., and D.-E. Xing. 2012. A new Neocalamites (Sphenophyta) with prickles and attached cones from the Upper Triassic of China. Palaeoworld (accepted manuscript). http://dx.doi.org/10.1016/j.palwor.2012.04.001

Abstract - Remains of the extinct sphenophyte (horsetail) Neocalamites are most widespread in the Middle–Upper Triassic and are typically represented by stem and leaf fragments. Here we report on spectacular new finds of Neocalamites from the Late Triassic Yangcaogou Formation in Liaoning Province, China that include bedding surfaces dominated by nearly complete aerial stems with attached leaf whorls and rare bractless cones. They reveal a monopodial growth habit for the stems, which are covered with downward projecting prickles that probably provided protection against herbivores. These features provide the basis for a new proposed species, Neocalamites horridus. The nodes bear whorls of very long leaves mainly free to their bases, and one specimen bears an attached cone on a long peduncle. Identical dispersed cones have also been recovered. The leaves of adjacent monopodial stems most likely interlocked to support growth in large stands akin to the role now played by branches in large modern Equisetum species. The new Chinese Neocalamites is among the most confidently reconstructed species, and indicates a greater diversity of sphenophyte morphology during the Mesozoic than previously realized.

Introducing Protome batalaria, a New Phytosaur from the Chinle Formation of Petrified Forest National Park, Arizona

In the Fall of 2004 Michelle Stocker and I were out at the Battleship NW fossil locality in Petrified Forest National Park with several researchers from Northern Arizona University. They were working on completing the geological map of the area and had noted that they could not get the current stratigraphic scheme we were using (introduced in 2002) to work out on the map.  The stratigraphic position of this quarry was an important issue behind this work as I had just collected a good skeleton of the aetosaur Calyptosuchus wellesi here just above a prominent sandstone that previous workers had correlated to the "Sonsela Sandstone Bed". If this bed correlation was correct then the specimen would be from the Revueltian biozone. This was problematic because Calyptosuchus is considered an index taxon of the Adamanian.  As we hemmed and hawed back and forth and discussed various possible correlations to work out these problems, Michelle noted some scraps of bone in unconsolidated sand at top of this bed and very near to where we were standing. She was very surprised, as was I, when she reached down and pulled up part of the skull roof of a phytosaur.

After the NAU researchers moved on to complete their work, we examined Michelle's new "quarry" much closer.  By literally sifting our fingers through the loose sand we easily collected numerous parts of the skull including large portions of the rostrum and skull roof. We also uncovered a ramus of the mandible, but this was actually in-situ in the bedrock just underneath the loose sand. We were able to jacket this element, but it was wintertime and I distinctly remember how frozen our hands were after each application of a plaster bandage.  Luckily the truck was very nearby, so after each application we would run to the running truck to stick our hands under the heater.

Back in the lab we were able to piece back together much of the skull and it later became part of the focus of Michelle's Masters Thesis. Prior to this Randall Irmis and I mentioned (and figured) this specimen in a 2005 paper where we referred it to "Leptosuchus" adamanensis based on the overall morphology of the squamosals following work by Long and Murry. However, Michelle's detailed phylogenetic analysis in her thesis suggested something different, specifically the specimen did not form a clade with Smilosuchus adamanensis and instead was something else.

In her new paper in the Journal of Vertebrate Paleontology Michelle has described this specimen as a new taxon, which she names Protome batalaria. The name reflects the condition of the specimen, "face of an animal" and where it was found "warship" (for the Battleship Quarry). It can be diagnosed by a unique combination of characters as well as three autapomorphies of the braincase and lower jaw. Her phylogenetic analysis recovers it as a non-pseudopalatine leptosuchomorph.

Important discussion in her paper revolves around the importance of the use of apomorphies to describe and classify specimens. In this particular case past workers (myself) had focused on the generally morphology of the squamosal and robustness of the specimen to make a taxonomic assignment and ignored other discrete apomorphies of the material, which a phylogenetic analysis later determined to be of significance.  Thus the longtime practice of assigning isolated phytosaur squamosals to taxa based on general similarity and utilizing these for Late Triassic biochronology is called into question. This general squamosal morphology used to assign (fragmentary and complete) specimens to Rutiodon or Leptosuchus instead just appears to be a shared character of non-pseudopalatine leptosuchomorphs, a paraphyletic assemblage.

As recommended by Michelle it is now necessary to go back to collections such as those from the Petrified Forest and look carefully at all of the specimens assigned to "Leptosuchus" and sort them out using apomorphies. Hopefully this will provide a clear distribution pattern and biochronological signal for these specimens, testing their importance in phytosaur biochronology and biogeography.  Overall this new paper provides a great description and discussion that Michelle should be proud of and will be landmark (along with her 2010 paper) for sorting out the labyrinth that is phytosaur taxonomy.

By the way, the stratigraphic problem mentioned at the beginning of this post was finally figured out by Jeff Martz and I in 2009 when we discovered that the bed in question was definitely not the "Sonsela Sandstone Bed", but rather an isolated sandstone lens in the older Lot's Wife Beds and  Adamanian in age.

Stocker, M. R. 2012. A new phytosaur (Archosauriformes, Phytosauria) from the Lot’s Wife beds (Sonsela Member) within the Chinle Formation (Upper Triassic) of Petrified Forest National Park, Arizona. Journal of Vertebrate Paleontology 32(3): 573-586 DOI:10.1080/02724634.2012.649815

Abstract - A new phytosaur taxon from Petrified Forest National Park, Arizona, is here described based on cranial material from a single individual. This specimen previously was included in an extensive phylogenetic analysis, and it was found to possess a combination of character states that differs from all known phytosaur taxa in addition to two autapomorphies within the braincase and an autapomorphy of the mandible. The new taxon adds to the taxonomic diversity recognized from the Sonsela Member of the Chinle Formation. The continued increase in phytosaur diversity emphasizes the need to more accurately characterize and identify taxa within a phylogenetic systematic context in order to produce a more refined signal for biostratigraphic correlations, biochronologic inferences, and faunal dynamics during the Late Triassic.