STL Science Center

STL Science Center

11 June 2020

An Exciting Opportunity

From the Facebook page of Julius Csotonyi:

A twist! On Sunday, join me in a drawing lesson on a rare modern-day survivor of the last ice age: the arctic ground squirrel or ᓯᒃᓯᒃ (pronounced "siksik") (Urocitellus parryii). Yukon paleontologist Dr. Grant Zazula will provide scientific commentary on this interesting (and large!) species of ground squirrel while I demonstrate its illustration, in an online event hosted by the Yukon Beringia Interpretive Centre at 1 pm Pacific Time on Sunday, June 14.

04 June 2020

Penguins Part II

Inkayacu, was approximately the same size as Palaeeudyptes

Fossil penguins were not always penguin "shaped", as we saw with Waimanu, but they became more distinctively penguin-like over time, as we saw with Kumimanu. Intermediate family members like Perudyptes and Anthropornis continue this "penguinification" trend of the overall body plan throughout the Eocene era and, by the times of Icadyptes, Palaeeudyptes, and Inkayacu, penguins look like the animals we think of when we hear the name penguin. There is one rather enormous exception to their recognizable penguin form: these are very tall penguins. Additionally, some of these penguins were likely still using their feet, in some capacity, in propulsion for swimming. Though we mentioned that it appeared as though Kumimanu may not be using its feet anymore to swim, it has been noted that the feet and ankles of some of these larger penguins indicate that they may have still played a role in swimming.The Eocene was an age of giant birds. Whereas the "Terror Birds" ruled portions of South America terrestrially, the giant penguins were taking to the ocean and at least terrorizing fish populations. Sharks were still apex predators in the ocean. Whales were in the process of fully transitioning from land to water. Enormous penguins could have been filling a niche that is now occupied by small whales and dolphins (and even smaller sharks like the reef sharks). Whatever their absolutely exact role, they were clearly highly successful birds that transitioned back from a terrestrial lifestyle to a nearly fully aquatic lifestyle. They did so as large animals that, over time, became increasingly efficient swimmers with streamlined bodies. Even if whales, dolphins, and smaller sharks (possibly seals and sea lions as well) pushed them into a finer definition of a niche, one which they currently occupy as pursuit predators. The nuances of penguin evolution, locomotion, diet, and the life histories of individual species are all complex topics that span the careers of scientists. Hopefully these two discussions are helpful in a very general sense to understanding penguins and their history.

01 June 2020

Penguins Part I

Waimanu manneringi ©Nobu Tamura
We know a lot about fossil penguins. Partly, this is because we have a fairly large number of fossils from penguins, which is a rarity for birds as a group in general. It's also a bit of a blessing. There are a number that are a little more well-known for various reasons (mostly to do with publication and news cycles) like Waimanu, Inkayacu, and Perudyptes; all penguins described since 2006. However, we have been recovering and describing penguin fossils since much earlier times: Pachydyptes (Oliver, 1930), Paraptenodytes (Ameghino, 1891), and Palaeosphenicus (Morino and Mercerat, 1891) are notable examples. Not all penguins are the same, so lumping them together is not really fair. However, their overall body plans are fairly conservative. Most members of the penguin family are recognizably penguin-like though ancestral members of the family are not exceptionally penguin-like. This includes Waimanu, an early member of the penguin family that has some penguin-like traits, but looks less like a penguin than we would imagine even an early penguin might appear. Waimanu has a longer tail and more wing-like upper limbs than we would expect a penguin to possess. However, its bill does look very much like the bill that we associate with fish catching birds and is reminiscent of that we see in penguins. The legs of Waimanu are more like those of a loon or a grebe and do not appear to be very useful for walking on land (just like those of loons and grebes). The position of the legs are better for swimming than for walking, to be honest, and from what we know about penguins, this makes a lot of sense.

Kumimanu biceae ©Nobu Tamura
Penguins do not swim with their legs though, they swim with their fins, their wings, providing propulsion underwater. So how does a penguin transition from leg power to wing power? The next oldest penguin we know (currently) from fossils, Kumimanu is decidedly more penguin-like. The feet look more like penguin feet. The tail is shorter than Waimanu's tail. The bill is still rather large and fish catching; not entirely penguin-like yet. We do have more flipper-like wings with Kumimanu, likely indicating that the legs are no longer propulsive and the flippers have taken over this function. The wings are not entirely like flippers that we see in modern day penguins though. Also, as we can see in Nobu Tamura's illustration, Kumimanu was a rather large early penguin. There are larger penguins that we know of, but rather than attempting to discuss all of the very important penguin fossils in one post, we will continue tomorrow with other notable penguins, some of which may be the largest penguins that ever lived.

25 May 2020

Long Distance Hugs

We could probably all use some kind of interaction from outside our family these days. While we cannot really pat one another on the back and continue social distancing, there are animals that could have done so. One such animal was the ornithomimosaur Deinocheirus mirificus. Originally, a pair of arms and their shoulders were described in 1970 by Osmólska & Roniewicz, and Deinocheirus was originally thought to be some kind of carnosaur. The description was amended after some time to assign Deinocheirus to the ornithomimosaurs, but new material to even more thoroughly describe the dinosaur was unknown for nearly 50 years. In 2014 (49 years after the initial dig that found Deinocheirus remains) new remains were found in Mongolia (later they were stolen but then returned to the country) from two individuals of the species. At an estimated 11 m and 6.4 t, this was a large and heavy ornithomimosaur of the Late Cretaceous.

The enormous hands and long arms are thought to have been well adapted for digging, which, given the duckbill-like head that seems adapted for water and grass foraging, appears to be at odds with the hypothesized diet. A large number of gastroliths associated with Deinocheirus support a vegetation heavy diet, as the dinosaur would have used these to help break down the fibrous plant matter. It has been reported that fish vertebrae were also discovered along with the gastroliths, meaning that it is likely that Deinocheirus was eating fish as well. Could oversized hands be useful for catching fish? There is a possibility for this as a use, but digging and manipulation of vegetation remains a good hypothesis.

Digging, with large hands, could help efficiently find supplemental dietary items like insects and burrowing lizards; there is no known evidence for this behavior currently. Also unknown is the nesting behavior of these animals. Could hands good at digging make very good nesting mounds? This is also a potential hypothesis. Holding vegetation to crop (or chop) small amounts of food could also be plausible. Defense could also be a plausible explanation for the namesake "horrible hands". Injuries to the holotype digit joints and bitemarks in the coracoids near the shoulder indicate manipulation of the digits (important for dexterous activities noted above) and unsuccessful predation. These predation events are attributed to one of the largest predators on Earth during the Cretaceous, Tarbosaurus bataar.
Adapted by Wiki users from the original at (

15 March 2020

Talk to me on Twitter!

Hello all!
You're stuck at home. You're loved ones are stuck at home. I'm stuck at home. I'll be working on lectures and moving my class (and helping colleagues move online) all week. However, if you, your friends, or those lovely students you've suddenly been locked in with are looking for dinosaur or ornithology information over the coming weeks I'd like to offer what I can.

From 9am - 12pm EST during the weekdays I'll leave my Twitter feed (@ornithanatomist) open to questions. Maybe I'll get a lot of questions, maybe I won't! If you have questions, though, ask and I'll answer, find an answer (if I can), or point you to a good source to find the answer.

Stay tuned here and on Twitter. As I'm able I may be able to work out themed question days. I may (time permitting) be able to set up live Q & A sessions as well. Stay tuned everyone.

02 February 2020

Fossil Squirrels?

Good morning! What a wonderful morning it is! Punxsutawney Phil came out and told us all that spring is right around the corner, which is a very big deal. This is a North American "tradition" that was adapted from a similar German tradition (Dachstag: "Badger day") involving the European badger. American badgers would be far less amicable to this sort of treatment I think. In Pennsylvania, Phil is kind of a big deal him(her?)self. Groundhogs (Marmota monax) make a somewhat lucrative life for themselves in the state, even being endorsed by the state lottery as a spokes... hog named Gus. It is also quite hard to walk near any wooded area of Pennsylvania without running into at least a few of these large animals scurrying about the edge of the forest. But what are they really?

Fear is an acceptable response.
The animal has a lot of common names: groundhog, woodchuck, Canada marmot, and, my personal favorite, whistlepig, are just a few. Groundhogs, by any name, are not actually pigs or hogs (they are in the same genus as marmots, so that name has some basis, though they are certainly found south of Canada), but instead, they are actually some of the larger members of the squirrel family. Specifically, as some of their common names somewhat allude to, they are ground squirrels. Groundhogs can climb, despite their name, and a groundhog in a tree is something worth seeing.

When we think of oversized anything in the animal kingdom we tend to think that the only place to look is in the fossil record. That is, after all, where we find giant sloths, oversized wolves, dinosaurs, and enormous terror birds. We know that they are fantastic digging animals and spend a lot of time, including hibernation in a burrow. Was there, then, an even more giant ground squirrel that burrowed extensively in the history of life? Fossilized burrows are known from much earlier than the current era. The first burrows belong to very early animals, but if we are looking for the recent ancestors of giant squirrels, we do not need to go that far back.

Photo of Clarkia, Idaho squirrel fossil by
Bill Richards, North Idaho College
The first squirrels in North America appear in the Late Eocene, around 41 to 33 million years ago. Any "squirrel-like" fossils from before this are not squirrels.
The first ground squirrels appear shortly after the Eocene, in the early Oligocene, at approximately 30 million years ago in Europe. As far as the marmots themselves, there is no clear consensus on when this large group of ground squirrels first appear in the fossil record. They are evident by the Late Oligocene in North America. It is acknowledged that by the time we have a good fossil record, in the Mid-Miocene, the ground squirrels, particularly prairie dogs, are already well-represented within their modern range. The fact that we recognize their fossils as highly similar to their extant morphology does not really bode well for finding the origins of Punxsutawney Phil and Gus' family though. Truly, the fact of the matter is that squirrels, as long as we have known them in the extinct and extant capacity, have looked pretty much like squirrels. One could almost say that rodents are kind of like the cockroach of the mammal family in that they have existed long enough to have "survived anything and everything" that life can throw at them. We may see if this remains true in our own lifetimes, but let us hope that we do not.

For more reading:

  • Helgen, Kristofer M.; Cole, F. Russell; Helgen, Lauren E.; Wilson, Don E. (April 2009). "Generic Revision in the Holarctic Ground Squirrel Genus Spermophilus" (PDF). Journal of Mammalogy. 90 (2): 270–305. doi:10.1644/07-MAMM-A-309.1. Archived from the original (PDF) on 2011-10-22.

  • Kryštufek, B.; B. Vohralík (2013). "Taxonomic revision of the Palaearctic rodents (Rodentia). Part 2. Sciuridae: Urocitellus, Marmota and Sciurotamias". Lynx, n. s. (Praha). 44: 27–138.

  • Steppan, Scott J.; Storz, B.L. &; Hoffmann, R.S. (2004): "Nuclear DNA phylogeny of the squirrels (Mammalia: Rodentia) and the evolution of arboreality from c-myc and RAG1". Mol. Phyl. Evol. 30(3): 703–719. doi:10.1016/S1055-7903(03)00204-5 PDF fulltext
  • 29 July 2019

    Non-crocodilian Face

    Holotype as depicted in von Baczko and Desojo, 2016
    The holotype skull of Riojasuchus is very non-crocodilian to the casual observer. Having previously been associated with a number of people interested in crocodiles this skull shapes is not very alien to me and others that have experiences like mine. This is far from the strangest of crocodilian ancestors of course and we have discussed others here before (such as Simosuchus). The ancestral variations and resulting evolutionary history of crocodilians is actually quite fascinating. Riojasuchus is somewhere in the middle of this history. It is, obviously I think, not quite a crocodile and not one of the "primitive" herbivorous crocodilian ancestors. Further separating Riojasuchus from its descendant cousins (possibly a more appropriate description than saying it is directly ancestral to crocodilians) is the tree of Butler et al. (2011) which describes Riojasuchus (and ornithsuchidae) as a lineage that ends without more descendant lineages. Regardless of whether Riojasuchus has extant descendants or not, the skull shape is decidedly non-crocodilian, which is what we wanted to look at specifically today. The teeth are more crcodilian than some other crocodile ancestors. The dorsoventrally tall skull is quite distinct from living crocodilians. The transition from skulls of this shape to the more familiar flattened skull of crocodilians is the subject of much ongoing inquiry and research. It is a long, complex story, and we are still learning quite a lot from this group of animals about how and why head shape changes, or does not, over the evolution of a group.

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

    Nesbitt, S. J., Desojo, J. B., & Irmis, R. B. (2013). Anatomy, phylogeny and palaeobiology of early archosaurs and their kin. Geological Society, London, Special Publications, 379(1), 1-7.