Terrific Tetanurae #13: Mirischia asymmetrica

The forest seems to whisper as the dry season pours into the land, stripping trees of their leaves and animals of their color. We’re in Cretaceous Brazil, and the land is dominated by forest. In these woods, every animal must fight to survive, from the smallest of fishes to the largest of dinosaurs. One animal in particular is suffering from the dry climate. The animal in question is an old Irritator bull. The animal is already at a disadvantage, having lost part of his left arm in a battle with another spinosaur. The wound has become infected, and the old bull’s immune system is not presently strong enough to fight off the bug. For now, the bull must rest and hope for better weather. Unfortunately, another predator has set its sights on the spinosaur, and not as a rival, but as food.

A month passes, and the old bull’s health has improved. The infection, however, has taken its toll on the animal, and the Irritator has become weak. He must find food or die. In the corner of his eye he spots movement. He moves closer, and observes a small coelurosaur chasing a juvenile pterosaur. This is Mirischia asymmetrica, the most common predator in these woods. The small coelurosaur, noticing the gigantic spinosaur, hisses and spreads its frill of feathers, which are colored bright blue to daze predators. The little tetanuran darts into the bushes. The spinosaur, knowing not to expend lots of energy on such a small catch, lumbers away. He’ll have to wait another day to eat.

Mirischia asymmetrica is a tyrannoraptoran from the Cretaceous of Brazil. This coelurosaur was assigned to compsogathidae (Rauhut et. al., 2010), a group of small, gracile meat eating dinosaurs. In fact, Mirischia asymmetrica is the only known compsognathid from the Americas. That depends on whether Mirischia is actually a compsognathid. In his book Tetrapod Zoology, Darren Naish suggested that M. asymmetrica might be a tyrannosauroid. Of course, this idea has been explored by the wonderful community of paleoartists.

Mirischia most likely hails from the Santana Formation of Brazil (Martill et. al., 2000), and, if so, would have shared its environment with many other archosaurs, including the spinosaurid Irritator (Weishampel et. al., 2004). This spinosaur may have been the apex predator of the Santana ecosystem, while smaller predators like Mirischia foraged for prey on the forest floor. Another small theropod, Santanaraptor, also called the Santana Formation home (Weishampel et. al., 2004). In time, the ancient forests of South America would loose the bloodline of Mirischia as other predators colonized the landscape.

During the Cenomanian, new groups of theropods started to take the throne of top predator. During the Jurassic and Early Cretaceous, the megalosaurs and allosauroids reigned as the top predators of ecosystems across the globe. During the Late Cretaceous, however, new groups of killer dinosaurs rose up the ranks. To the north, the members tyrannosauroid group, of which Mirischia might belong to (and, if not, was closely related to) developed larger sizes to go after larger prey.

The skull of T. rex, a tyrannosaurid tyrannosauroid dinosaur. Photo by the author, 2015.
The skull of T. rex, a tyrannosaurid tyrannosauroid dinosaur. Photo by the author, 2015.

In the south, another group of carnivorous dinosaurs rose to the top. These were the abelisaurids, relatives of the Jurassic Ceratosaurus. In the Late Cretaceous, these blunt-faced, stubby-armed marauders would conquer the ecosystems of the southern hemisphere, leaving other large carnivores of other predatory groups few and far between.

The skull of Majungasaurus crenatissimus, an abelisaurid. Photo by the author, 2015.
The skull of Majungasaurus crenatissimus, an abelisaurid. Photo by the author, 2015.

In this way, the tyrannosauroids might have been prevented from conquering the south, and the domain of Mirischia fell to a rival group of killer dinosaurs.

Mirischia   by the author. Pencils on paper, 2015.
Mirischia by the author. Pencils on paper, 2015.

References 

1. Rauhut, O. W. M.; Milner, A. C.; Moore-Fay, S. 2010. “Cranial osteology and phylogenetic position of the theropod dinosaur Proceratosaurus bradleyi (Woodward, 1910) from the Middle Jurassic of England.” Zoological Journal of the Linnean Society 158(1):155-195. 

2. Naish, Darren. 2010. Tetrapod Zoology Book One. Bideford: CFZ Press. p. 235. 

3. Weishampel, D. B; Dodson, P.; Osmólska, H. 2004. “Dinosaur distribution (Early Cretaceous, South America).” In: Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd Edition, Berkeley: University of California Press. Pp. 563-570.

A response to The Tetrapod Zoology Podcast #45: Why Lambeosaurines did, in fact, persist into the Maastrichtian

A response to The Tetrapod Zoology Podcast #45: Why Lambeosaurines did, in fact, persist into the Maastrichtian

Recently episode #45 of the acclaimed Tetrapod Zoology Podcast was released, and, as usual, I found time to listen to it while illustrating for the Appalachia book. One point made by Darren Naish, however, caught my ear. While illustrating a point on the decline of the decadently frilled ceratopsians and crested lambeosaurines, he suggested that none of them persisted to the Late Maastrichtian. That might be true for the former of the two dinosaur groups, but the latter still hung to life in the-you-know-what continent. That’s right, Maastrichtian lambeosaurine bones have been found in deposits from Appalachia. Let me elaborate…

While in the west crestless forms like Edmontosaurus were almost the only surviving genera of the hadrosaurid lineage, the eastern shores of the newly-formed North American continent seem to still have supported the crested magnificence of the lambeosaurine hadrosaurs.

Edmontosaurus, everyone's  (except for me!) favorite Maastrichtian hadrosaur in all its glory. Photo by the author, 2014.
Edmontosaurus, everyone’s (except for me!) favorite Maastrichtian hadrosaur in all its glory. Photo by the author, 2014.

Indeterminate remains of a lambeosaurine have been reported from the Navesink Formation of New Jersey not only from one, but two localities. The Navesink Formation itself is a Maastrichtian deposit dating from around 70-66 million years ago. Gallagher (1993) reported indeterminate lambeosaurine remains from the West Jersey Marl Company’s Pit, Barnsboro, New Jersey, and Gallagher (2002) reported of indeterminate lambeosaurine remains from the Inversand Company marl pit locality in Gloucester County, New Jersey. It certainly seems a lambeosaurine was present in the Navesink ecosystem.

This is the partial leg of a juvenile Corythosaurus casuarius, a lambeosaurine dinosaur. Photo by the author, 2015.
This is the partial leg of a juvenile Corythosaurus casuarius, a lambeosaurine dinosaur. This specimen was collected in South Dakota. Photo by the author, 2015.

Lambeosaurine remains have also been reported from elsewhere on Appalachia. Rich et. al. (1997) reported Lambeosaurine remains from the Maastrichtian of the Kanguk Formation. The occurrence of lambeosaurine remains in the Kanguk Formation not only has implications for the survival of lambeosaurines into the Maastrichtian, but also for the presence of possible “polar dinosaurs” in eastern North America.

It seems as though as they declined in the west, lambeosaurines still thrived in the east up until the very end of the Mesozoic.

Although I am being nitpicky with this short write-up, my goal is to emphasize the importance of research before stating scientific claims. I don’t mean to offend either Darren or John, but I wanted to catch this little sliver of misinformation.

References 

1. Gallagher, W. B. 1993. “The Cretaceous/Tertiary mass extinction event in the North Atlantic coastal plain.” The Mosasaur 5:75-154.

2. Gallagher, W. B. 2002. “Faunal changes across the Cretaceous-Tertiary (K-T) boundary in the Atlantic coastal plain of New Jersey: restructuring the marine community after the K-T mass-extinction event.” Catastrophic Events and Mass Extinctions: Impacts and beyond. GSA Special Paper 356:291-301.

3. Rich, T. H.; Gangloff, R. A.: Hammer. W. R. 1997. “Polar dinosaurs.” In P. J. Currie & K. Padian (eds.) Encyclopedia of Dinosaurs. San Diego: Academic Press. pp. 562-573.

Time for some Geology!

Time for some Geology!

Apart from the collecting I’ve done so far in Colorado (which, by the way, has turned up really nothing good), I have also gotten to witness some really interesting Rock Mountain geology. Here are a few highlights:

1. Beaver Lake

This lake, formed by glaciers and fed by snowfields, is situated above the resort town of Beaver Creek, and is home to trout and, of course, beavers, among other things. So far, my ventures have taken me to the lake twice, the first ascent more pleasant then the second, in which I was subject to two thunderstorms. Here are a couple pictures: IMG_4988

IMG_5023IMG_4997

I’ve also managed to witness some pretty beautiful sunsets and their affect on the color of the Gore range. Some peaks in the range rise to more then 13,000 feet above sea level, but all are under 14,000 feet. I managed to snap the pictures below during what became a very, very pretty evening.

IMG_5089

IMG_5082Finally, check out Cross Creek, a small waterway which, this year, rose to a point where I was scared to cross the bridge above it, lest I be washed away in the white water rapids!

IMG_4828That’s all for now, but stay tuned for more updates on the book and on the collecting trips. Thanks for reading!

Book Update 1: Salamanders are weird, guys!

What does almost two days of continuous writing due to someone? It makes them salamander-crazy. I’ve been working on the chapter discussing lissamphibians and I think I might go nuts! I must have read the description paper for Parrisia neocesariensis 16 times, if not more! Lissamphibians are a lot cooler then many give them credit for. At the Ellisdale site, a Marshalltown Formation storm deposit in New Jersey, so many incomplete fossil specimens of salamanders and frogs have been collected that it’s hard to keep track of them. We’re talking weird-looking salamanders extremely adapted for an aquatic lifestyle (these guys have serpentine bodies!!) that could grow up to a foot long and probably had an extremely wide gape. Then there are the frogs, and the indeterminate stuff, and so on, and so on. If you haven’t researched Mesozoic lissamphibians (which, I should mention, are rare in the fossil record), you should do so sometime as some of them are really interesting animals.

I am going to highlight Parrisia neocesariensis, which I believe to be one of the most fascinating animals known from the Cretaceous of New Jersey. The animal is classified as a batrachosauroidid salamander known from partial remains collected at Ellisdale (Denton Jr. & O’Neill, 1998). Batrachosauroidid salamanders are thought to be large, streamlined marine amphibians (the Florida Museum of Natural History’s website suggest a length of three feet or more for Batrachosauroides dissimulans, a species of batrachosauroidid). Long stalks on the occipital condyles indicate these salamanders had wide gapes. So we have a long, marine salamander that could open its mouth real wide present in the Late Cretaceous of New Jersey. Wow!

I’m Writing a Book

I was going going to make myself write one sometime, so why not now?

A few months ago, I got the idea to write a book about the prehistoric landmass called Appalachia. This is actually what inspired me to do Antediluvian Beasts of the East. You might be asking why I haven’t shared this earlier. Well, I just didn’t know if I would write a book until around 3 months ago. Dave Hone’s post also gave me confidence to announce this.

So far, the working title is Appalachia Prehistorica, although I doubt that will stay. If you have any suggestions on a title, feel free to comment below. I’ll be giving updates on this blog periodically. Let’s hope it goes well.

Terrific Tetanurae #12 : Mahakala omnogovae

Terrific Tetanurae #12 : Mahakala omnogovae

In light of a recently discovered short-armed dromaeosaur, this friday we will check out another short-armed member of the family. Enter Mahakala omnogovae. 

75 million years ago, and Mongolia is covered by dry, somewhat barren plains intermingled with small forests, oases, and lakes. As a group of Pinacosaurus wander by a small forest, a male Velociraptor tries to attract mates using his colorful plumage. Suddenly, something catches the Velociraptor’s eye, and curiosity gets the better of him. He starts to jog toward the small theropod, which, in response, dashes away faster then the male Velociraptor can run. The male Velociraptor, somewhat depressed on not catching the theropod, a Mahakala, trots back to his post to continue his courtship display.

Meanwhile, the Mahakala dashes along the dry forest floor, searching for a meal. Suddenly, the Mahakala spots a small lizard, and slowly creeps toward the reptile. The Mahakala strikes and catches the lizard. It will be enough to sustain the dinosaur for the day, but soon hunger will require the animal to hunt again.

At approximately seventy centimeters long (Turner et. al., 2007), Mahakala was no giant predator. Mahakala was also found by Turner et. al. (2007) to be the most basal known dromaeosaurid. This animal is known from a partial skeleton, including portions of the skull (Turner et. al., 2007). As it turns out, the holotype represents what was either a young adult or a near-adult Mahakala. This was a mini-dromaeosaurid, indeed!

It is certainly possible this animal went after small prey such as insects, arthropods, and small lizards. I imagine the small dromaeosaurid darting across the ancient Mongolian landscape, snatching early wasps and the like from the ground, like a sort of ancient land-bound American kestrel. Mahakala might have also fallen prey to the larger dromaeosaurids and troodontids it co-existed with, including the famous Velociraptor and Saurornithoides. 

The iconic skull of Velociraptor mongoliensis at the American Museum of Natural History.
The iconic skull of Velociraptor mongoliensis at the American Museum of Natural History. Photo by the author, 2015.
Holotype skull of Saurornithoides at the American Museum of Natural History. Photo by the author, 2015.
Holotype skull of Saurornithoides at the American Museum of Natural History. Photo by the author, 2015.

Yet, as with almost every animal to have existed on Earth, Mahakala succumbed to extinction. The dromaeosaurids themselves would survive for around another 10 million years, when, during one of the largest extinction events in Earth’s history, an asteroid hit the planet we call home, causing drastic global environmental changes and damage. Mahakala itself would be remembered by the specimen of a young adult, locked away in a tomb of sandstone.

Mahakala omnogovae by the author. Pencils on paper, 2015.
Mahakala omnogovae by the author. Pencils on paper, 2015.

References

1. Turner, A. H.; Pol, D.; Clarke, J. A.; Erickson, G. M.; Norell, M. .2007. “A basal dromaeosaurid and size evolution preceding avian flight.” Science 317(5843): 1378–1381.

A Few Words on David Raup

As I’m sure some of you know, the first president of the Paleontological Society, passed away today at the age of 82. In remembrance, I’d like to share how his work helped me to become interested in the isolation and extinction of the paleofauna of Appalachia.

Some time ago, I read a little of his work on extinction patterns. Although I didn’t (and still don’t) agree with some of his theorems, his work got me interested in the gradual decline of species. His work opened me up to papers on extinction. Eventually, I stumbled upon one or two papers documenting the K-T extinction event on Appalachia, and I was hooked. Thank you, David Raup, for helping to position me down the road I have taken to this day. You will be missed.

My condolences go out to his family and friends during this sad time. If you have a story about Mr. Raup, please feel free to comment below.