This blog is about the lesser known side of the Archosaur tree - the branch that leads to crocodiles, instead of birds - the Crurotarsi. I started this blog as a way to teach myself more about these animals as well as to keep all crurotarsan enthusiasts up to date on the research associated with this clade.
My job doesn't always leave me with as much time as I would like to read all the papers as thoroughly as I would prefer. Also, there is a lot of work being done on the Triassic right now, so things are changing pretty rapidly. So please, if anyone finds any errors or notices that something is out of date, let me know! We all know the importance of peer review ; )
Crurotarsi vs. Avemetatarsalia
Archosaurs ("ruling reptiles", Cope 1869) are easily recognized by one of their major synapomorphies - the antorbital fenestra - an opening in the skull that lies between the nostrils and the eyes. The two extant clades (birds and crocodiles) are representatives of the two most specious and diverse groups of archosaurs: Avemetatarsalia (birds and everything closer to birds than to crocs, including dinosaurs and pterosaurs) and Crurotarsi (crocs and everything closer to crocs than to birds). These two clades are distinguished in part by the way that their ankles articulate, hence the name Crurotarsi, meaning "cross-ankles". The large majority of relationships within avemetatarsalia have been resolved, but Crurotarsi remains problematic. This is at least part of the reason for crurotarsans being the "forgotten archosaurs".
Crurotarsi vs. Pseudosuchia vs. Thecodontia
In the literature, several names tend to appear for taxa that are more closely related to crocodiles than to birds, namely Crurotarsi ("cross-ankles" Sereno 1991), Pseudosuchia ("false crocodiles" Zittel 1887-1890), and Thecodontia ("socket-toothed" Owen 1859).
I use Crurotarsi, but it is essentially interchangeable with Pseudosuchia, especially given the recent work by Sterling Nesbitt (see "The Early Evolution of Archosaurs: Relationships and the Origin of Major Clades" in the Bulletin of the American Museum of Natural History, 2011). The two can basically be defined as anything closer to crocs than to birds. In posts, when discussing a specific paper, I will use the name that is used by the author; otherwise, I will us Crurotarsi. I have yet to see a convincing argument for why one should be used over the other (although Bill Parker's argument for Pseudosuchia isn't half bad), so right now it is a matter of personal preference and I really don't like the idea of calling crocodiles "false crocodiles".
Thecodontia is an obsolete, paraphyletic, junk taxon. Pretty much any archosaur that was not a dinosaur, pterosaur, or crocodilian was called a thecodont. Several other names have appeared, such as "Crocodylotarsi", but are rarely used.
As you may have read in my profile, I have a B.S. in Geology from the University of Maryland, but that is as far as I have gotten thus far in my education, so I am in no way an expert in any field of paleontology. However, I have had my hand in several of the paleontological pots over the years and I am determined to get my Ph. D. in Paleontology and study the very animals that this blog is about. The best way to learn is to teach, so I'm starting as early as possible in acquiring a vast body of knowledge on my favorite clade. But for those of you who are interested, I will tell you of what experience I do have in paleontology.
My enthusiasm for all things extinct began at age 5 (1992) when I first experienced Dinosaur National Monument (as well as movies like The Land Before Time and Jurassic Park), but that was only the start.
In 2005, I entered the University of Maryland as a geology major and a student in the College Park Scholars: Earth, Life, and Time program (an academic program focusing on natural history) which was run by two great paleontologists: Dr. Tom Holtz and Dr. John Merck. Many of you probably know who Dr. Holtz is and if you don't, then either you don't own a television or you have absolutely no interest in T. rex. In either case, shame on you.
But my first real experience didn't come until 2007, when I spent a semester reconstructing the jaw of a Cetothere (a Miocene Baleen whale) in the FossiLab at the National Museum of Natural History in D.C.. I worked with Steve Jabo, one of the fossil preparators, and aside from putting the whale back together, I also sorted thru pieces of dinosaur bone collected from the previous field season. I took every paleo-related class offered at the university and even sat in on Dr. Holtz's graduate class on archosaurs whenever I had the chance.
My senior year, I finally got to try my hand at research. I worked with Dr. Scott Wing (Curator of Fossil Plants at the NMNH) and Dr. Jay Kaufman (a geochemist at UMD) to determine paleoclimate data (using Leaf Margin Analysis) and C and N isotope shifts during the Paleocene Eocene Thermal Maximum (PETM), about 55 Ma. I prepared and organized over 100 leaf specimens collected from the Bighorn Basin in Wyoming. I never published my findings because of the large error for the mean annual temperature values I calculated (not enough angiosperm species) and the limited isotopic data I was able to gather (time constraints and a broken mass spectrometer meant very poor resolution for isotope curves). However, my work (paper and poster)can be found at the UMD Geology Department's website.
In the summer of 2011, I was an intern at Petrified Forest National Park, working with Bill Parker. We spent most days wondering the park looking for fossils. I seemed to have a particular talent for finding aetosaur osteoderms, but I also managed to find a phytosaur skull. I definitely plan on returning next summer. Read more in the blog posts I wrote about it all: Part 1, Part 2, Part 3, and Part 4.
I am now in the process of applying to grad schools, so look out!
My research interests are mostly in rauisuchians, as well as major transitions in earth history (especially extinction events) and their effects on evolutionary patterns. Here's more of an official list:
- Systematics and paleontology of crurotarsan/pseudosuchian archosaurs, especially basal loricatans
- Triassic terrestrial vertebrate paleoecology, biogeography, biostratigraphy, and taphonomy
- Terrestrial ecosystem evolution and response to major transition events