New Blog

Back at the beginning of the year I had this post on my American Civil War interests. Much of this stems from the letters and diary I have from an ancestor who fought in the war. I've been researching these letters and his regiment for almost 20 years now in hopes of someday putting it in book form. I've realized that this is not going to happen anytime soon, so what I have decided to do in the meantime is put portions of this research in blog form to share with other enthusiasts.

So I am happy to announce the launch of a new blog titled "three month men" which essentially is a study of the First Connecticut Volunteer Regiment in the American Civil War, chiefly through the words of one of the participants. What will be presented is my ancestor's role in the American Civil War, portraying events from the end of 1860 through the days after the First Battle of Bull Run in April of 1861. I will present excerpts from his diary and letters and the posts will be ordered chronologically and cover a day or two of time. Thus I hope that people will be interested in following his story as the blog progresses. Furthermore, I hope to provide information on a poorly known military unit. As this will truly be a side project I hope to post new material once a week or biweekly. If any of my Triassic readers have a soft spot for American history, in particular the Civil War, I welcome you to follow along. I hope that you will find it of interest.

www.threemonthmen.blogspot.com

Ectothermic Bovids? Is Nothing Sacred?

OK...this is pretty far out from the Triassic, but really interesting so I thought I'd share.

Kohler, M., and S. Moya-Sola. 2009. Physiological and life history strategies of a fossil large mammal in a resource-limited environment. Early online, PNAS. doi: 10.1073/pnas.0813385106

Abstract - Because of their physiological and life history characteristics, mammals exploit adaptive zones unavailable to ectothermic reptiles. Yet, they perform best in energy-rich environments because their high and constant growth rates and their sustained levels of resting metabolism require continuous resource supply. In resource limited ecosystems such as islands, therefore, reptiles frequently displace mammals because their slow and flexible growth rates and low metabolic rates permit them to operate effectively with low energy flow. An apparent contradiction of this general principle is the long-term persistence of certain fossil large mammals on energy-poor Mediterranean islands. The purpose of the present study is to uncover the developmental and physiological strategies that allowed fossil large mammals to cope with the low levels of resource supply that characterize insular ecosystems. Long-bone histology of Myotragus, a Plio-Pleistocene bovid from the Balearic Islands, reveals lamellar-zonal tissue throughout the cortex, a trait exclusive to ectothermic reptiles. The bone microstructure indicates that Myotragus grew unlike any other mammal but similar to crocodiles at slow and flexible rates, ceased growth periodically, and attained somatic maturity extremely late by ~12 years. This developmental pattern denotes that Myotragus, much like extant reptiles, synchronized its metabolic requirements with fluctuating resource levels. Our results suggest that developmental and physiological plasticity was crucial to the survival of this and, perhaps, other large mammals on resource-limited Mediterranean Islands, yet it eventually led to their extinction through a major predator, Homo sapiens.

This is open access from:

www.pnas.orgcgidoi10.1073pnas.0813385106

More Scenes From the Chinle Formation

More Chinle scenery from our recent fieldwork. Enjoy.

Aardonyx celestae, a New Transistional Sauropodomorph from the Early Jurassic of South Africa

Yates, A. M., Bonnan, M. F., Neveling, J., Chinsamy, A., and M. G. Blackbeard. 2009. A new transitional sauropodomorph dinosaur from the Early Jurassic of South Africa and the evolution of sauropod feeding and quadrupedalism. Proceedings of the Royal Society B. doi:10.1098/rspb.2009.1440. Published online

Abstract - Aardonyx celestae gen. et sp. nov. is described from the upper Elliot Formation (Early Jurassic)of South Africa. It can be diagnosed by autapomorphies of the skull, particularly the jaws, cervical column, forearm and pes. It is found to be the sister group of a clade of obligatory quadrupedal sauropodomorphs (Melanorosaurus + Sauropoda) and thus lies at the heart of the basal sauropodomorph–sauropod transition. The narrow jaws of A. celestae retain a pointed symphysis but appear to have lacked fleshy cheeks. Broad, U-shaped jaws were previously thought to have evolved prior to the loss of gape-restricting cheeks. However, the narrow jaws of A. celestae retain a pointed symphysis but appear to have lacked fleshy cheeks, demonstrating unappreciated homoplasy in the evolution of the sauropod bulk-browsing apparatus. The limbs of A. celestae indicate that it retained a habitual bipedal gait although incipient characters associated with the pronation of the manus and the adoption of a quadrupedal gait are evident through geometric morphometric analysis (using thin-plate splines) of the ulna and femur. Cursorial ability appears to have been reduced and the weight bearing axis of the pes shifted to a medial, entaxonic position, falsifying the hypothesis that entaxony evolved in sauropods only after an obligate quadrupedal gait had been adopted.

Defining Silesauridae

The new paper by Max Langer and collaborators (Langer et al., 2009) provides a phylogenetic definition for the clade Silesauridae. Silesaurids are gracile, quadrupedal, hebivorous/omnivorous dinosauriforms whose first announcement in 2003 (Dzik, 2003) generated a large amount of interest in early dinosaur phylogeny. In fact there were at least five presentations at this years SVP meeting alone that dealt with silesaurs.

Langer et al. (2009) define Silesauridae as "all archosaurs closer to Silesaurus opolensis, than to Heterodontosaurus tucki and Marasuchus lilloensis". Currently it is pretty much agreed that Silesauridae contains Silesaurus opolensis, Sacisaurus agudoensis, Eucoelophysis baldwini, and Pseudolagosuchus major (Nesbitt et al., 2005; Ezcurra, 2006; Irmis et al., 2007b; Langer et al., 2009). Silesaurus also possibly contains Lewisuchus admixtus, Technosaurus smalli, and an isolated specimen from Petrified Forest National Park (Irmis et al., 2005; Parker et al., 2006; Nesbitt et al., 2007; Langer et al., 2009).

Since their first publication it has been debated whether this clade represent dinosauriforms (e.g., Parker et al., 2006; Irmis et al., 2007a; Nesbitt et al., 2007) or possibly basal ornithischians (e.g., Ferigolo and Langer, 2007; Dzik and Sulej, 2007). Currently there is much more support for placement as the sister taxon of Dinosauria (Ezcurra, 2006; Irmis et al. 2007b, Langer et al., 2009). Nonetheless, silesaurids most likely filled an ecological niche later filled by ornithischian and thus possibly supressed early ornithischian diversity through the Late Triassic.

REFERENCES

Dzik, J. 2003. A beaked herbivorous archosaur with dinosaur affinities from the early Late Triassic of Poland. Journal of Vertebrate Paleontology 23:556-574.

Dzik, J., and T. Sulej. 2007. A review of the Early Triassic Krasiejow biota from Silesia, Poland. Paleontologia Polonica 64:3-27.

Ezcurra, M. D. 2006. A review of the systematic position of the dinosauriform archosaur Eucoelophysis baldwini from the Upper Triassic of New Mexico, U.S.A. Geodiversitas 28:649-684.

Ferigolo, J. and M. Langer. 2007. A late Triassic dinosauriform from south Brazil and the origin of the ornithischian predentary bone. Historical Biology 19:23-33.

Irmis, R. B., Parker, W. G., and S. N. Nesbitt, 2005. Critical review of the Late Triassic dinosaur record, part 2: Ornithischia. Society of Vertebrate Paleontology 25(3):73A.

Irmis, R. B., Parker, W. G., Nesbitt, S. J., and J. Liu, 2007. Early ornithischian dinosaurs: the Triassic Record. Historical Biology 19:3-22.

Irmis, R. B., Nesbitt, S. J., Padian, K., Smith, N. D., Turner, A. H., Woody, D., and A. Downs. 2007. A Late Triassic dinosauromorph assemblage from New Mexico and the rise of dinosaurs. Science 317:358-361.

Nesbitt, S. N., Irmis, R. B., and W. G. Parker, 2005. Critical review of the Late Triassic dinosaur record, part 3: Saurischians of North America. Society of Vertebrate Paleontology 25(3):96A.

Nesbitt, S. J., Irmis, R. B., and W. G. Parker. 2007. A critical reevaluation of the Late Triassic dinosaur taxa of North America. Journal of Systematic Palaeontology 5:209-243.

Parker, W. G., Irmis, R. B., and S. J. Nesbitt. 2006. Review of the Late Triassic dinosaur record from Petrified Forest National Park, Arizona. Museum of Northern Arizona Bulletin 62:160-161.

New Paper on the Origin and Early Evolution of Dinosaurs

Langer, M.C., Ezcurra, M.D., Bittencourt, J.S., and F.E. Novas. 2009. The origin and early evolution of dinosaurs. Biological Reviews 84:1-56. doi:10.1111/j.1469-185X.2009.00094.x

ABSTRACT-The oldest unequivocal records of Dinosauria were unearthed from Late Triassic rocks(approximately 230 Ma)accumulated over extensional rift basins in southwestern Pangea. The better known of these are Herrerasaurus ischigualastensis, Pisanosaurus mertii, Eoraptor lunensis, and Panphagia protos from the Ischigualasto Formation, Argentina, and Staurikosaurus pricei and Saturnalia tupiniquim from the Santa Maria Formation, Brazil. No uncontroversial dinosaur body fossils are known from older strata, but the Middle Triassic origin of the lineage may be inferred from both the footprint record and its sister-group relation to Ladinian basal dinosauromorphs. These include the typical Marasuchus lilloensis, more basal forms such as Lagerpeton and Dromomeron, as well as silesaurids: a possibly monophyletic group composed of Mid-Late Triassic forms that may represent immediate sister taxa to dinosaurs. The first phylogenetic definition to fit the current understanding of Dinosauria as a node-based taxon solely composed of mutually exclusive Saurischia and Ornithischia was given as ‘‘all descendants of the most recent common ancestor of birds and Triceratops’’. Recent cladistic analyses of early dinosaurs agree that Pisanosaurus mertii is a basal ornithischian; that Herrerasaurus ischigualastensis and Staurikosaurus pricei belong in a monophyletic Herrerasauridae; that herrerasaurids, Eoraptor lunensis, and Guaibasaurus candelariensis are saurischians; that Saurischia includes two main groups, Sauropodomorpha and Theropoda; and that Saturnalia tupiniquim is a basal member of the sauropodomorph lineage. On the contrary, several aspects of basal dinosaur phylogeny remain controversial, including the position of herrerasaurids, E. lunensis, and G. candelariensis as basal theropods or basal saurischians, and the affinity and/or validity of more fragmentary taxa such as Agnosphitys cromhallensis, Alwalkeria maleriensis, Chindesaurus bryansmalli, Saltopus elginensis, and Spondylosoma absconditum. The identification of dinosaur apomorphies is jeopardized by the incompleteness of skeletal remains attributed to most basal dinosauromorphs, the skulls and forelimbs of which are particularly poorly known. Nonetheless, Dinosauria can be diagnosed by a suite of derived traits, most of which are related to the anatomy of the pelvic girdle and limb. Some of these are connected to the acquisition of a fully erect bipedal gait, which has been traditionally suggested to represent a key adaptation that allowed, or even promoted, dinosaur radiation during Late Triassic times. Yet, contrary to the classical ‘‘competitive’’ models, dinosaurs did not gradually replace other terrestrial tetrapods over the Late Triassic. In fact, the radiation of the group comprises at least three landmark moments, separated by controversial (Carnian Norian, Triassic-Jurassic) extinction events. These are mainly characterized by early diversification in Carnian times, a Norian increase in diversity and (especially) abundance, and the occupation of new niches from the Early Jurassic onwards. Dinosaurs arose from fully bipedal ancestors, the diet of which may have been carnivorous or omnivorous. Whereas the oldest dinosaurs were geographically restricted to south Pangea, including rare ornithischians and more abundant basal members of the saurischian lineage, the group achieved a nearly global distribution by the latest Triassic, especially with the radiation of saurischian groups such as ‘‘prosauropods’’ and coelophysoids.

More Free PDFs

Paläontologische Zeitschrift, now published by Springer, is offering open access for the month of November only.

http://www.springerlink.com/content/0031-0220?sa_campaign=email/PROM/PSE11800_V1

The New Mexico Museum of New Mexico and Science is also offering free PDFs of many of its published bulletins. Obviously there are lots of free Triassic PDFs here but the one that I highly recommend is Bulletin #4 (Long and Murry, 1995 - Late Triassic Carnian and Norian Tetrapods from the Southwestern United States). Although becoming dated it is still one of the quintessential references for anyone interested in Late Triassic vertebrates of the American southwest (and one of the most cited Triassic references ever). This has been out of print for awhile and those who have copies know that they were poorly bound and thus most existing copies are in tatters. Here is your chance to get the volume in its entirety.

http://econtent.unm.edu/cdm4/document.php?CISOROOT=/bulletins&CISOPTR=659&REC=6

BTW...you'll have to turn off your pop-up blocker to get the bulletin.