Ceratosaurus Part 1: The history of a predatory horned dinosaur.

Disclaimer: I promised you all a post about the teeth of Ceratosaurus. This is not that post. In reviewing the history of Ceratosaurus I found the post growing with background knowledge but no discussion of teeth. It make sense; there is backstory here dating back to Marsh in the 1880s! So I have decided to break this into two posts. The first post, this one, covers the history of Ceratosaurus research. The next post, out soon, will cover just the dental aspects of this charismatic animal.

Ceratosaurus, the "horned lizard," was cool beast, no doubt about it! Here we have a theropod with huge fangs that was over 20 feet long, and had bone studded armor along its back! And that is to say nothing about those flamboyant crests on its face; one sits above its nose and another one above each of its eye. It was initially described by Marsh back in 1884 and is relatively well known thanks to a number of specimens from across the American West, mainly in Colorado and east-central Utah. There are large animals, presumed to be adults, and smaller individuals (presumably juveniles) in our sample as well, so we should theoretically have a good grasp on what this animal was like. Let's take a look at the history of Ceratosaurus, starting after Marsh's initial publication.

Gilmore in 1920 redescribed Marsh's animal (thankfully!) and revised the diagnosis for Ceratosaurus. I have quoted him in full below.

Generic characters: Premaxillaries with three teeth; maxillaries with 15 teeth; dentary with 15 teeth; 9 cervical vertebrae plano-concave; dorsal vertebrae biconcave; 5 sacrals; distal caudals without special lengthening of prezygapophyses; pelvis coossified; pubis with closed obturator foramen; 4 digits in manus, first and fourth reduced; probably 3 digits in pes; dermal ossifications; abdominal ribs present.

Plate 17, Figure 1 from Gilmore (1920), showing the right side of the holotype of Ceratosaurus

Plate 17, Figure 2 from Gilmore (1920), showing the left side of the holotype of Ceratosaurus

This is a workable definition for the time but we know that some of these are not autapomorphies (things found only in one type of organism). In fact, some of these characters are ancestral for theropods, or even archosaurs. Still, we can't fault Gilmore. He was working with what comparative material he had at the time and did an excellent job. Perhaps most outstanding, even compared to papers being published in the 21st century, are his excellent illustrations of the material he is describing.

That same year (1920), Werner von Janensch published on several theropods recovered by German expeditions to the Tendaguru beds. The most famous of these is probably Elaphrosaurus bambergi, a medium sized ceratosaur subject to much speculation in the decades since. In this same publication Janensch commented on the presence of Allosaurus, which he later named Allosaurus tendagurensis (Janensch, 1925), though this has been suggested to be a carcharodontosaurid. Additionally, and relevant to the post here, he identified Ceratosaurus (?) sp., Megalosaurus (?) ingens, and Labrosaurus stechowi from the same beds.

The butt of Elaphrosaurus on display in Berlin during the 2014 SVP meeting.

Tibia, teeth, and dorsal vertebra of "Allosaurus tendagurensis", also on display in Berlin. Whatever it was, it was big.

 Janensch didn't illustrate his Ceratosaurus sp., which was based on three dorsal vertebrae, but he did illustrate his "Megalosaurus" ingens and "Labrosaurus" stechowi. These will be relevant to our discussion on the teeth of Ceratosaurus.

Figure 6 from Janensch (1920) with the tooth of  Megalosaurus (=?Ceratosaurus) ingens

Figures 7 & 8 from Janensch (1920) with a ?labial and basal view of the tooth of  Labrosaurus stechowi (=?Ceratosaurus sp.)

Work continued sporadically on the genus. In 1963 Jim Madsen and William Stokes presented at the Geological Society of America meeting in Provo about new material from the Cleveland-Lloyd Quarry in central Utah. It was obvious that there was more to this animal than had been previously described. The last (so far) phase in new Ceratosaurus species came in 2000 when Madsen and Sam Welles named two new species: C. magnicornis and C. dentisulcatus. C. magnicornis was so-named from its large nasal horn, while C. dentisulcatus derives its specific name from grooves Madsen and Welles saw on the premaxillary and anterior dentary teeth; this taxon included the remains initially described in that 1963 abstract, while C. magnicornis was named from remains found in western Colorado.

Your faithful author with part of the holotype of Ceratosaurus magnicornis at Dinosaur Journey in Fruita, Colorado

In addition to coining two new species, Madsen and Welles looked over the material that had previously been assigned to the genus by other workers, including the material from Tendaguru. This was the most comprehensive review of all the material assigned to Ceratosaurus to date. Here's a summary of their findings.

• Ceratosaurus roechlingi (Janensch 1925) may be a very large Ceratosaurus but isn't diagnostic past Ceratosaurus sp.
• Labrosaurus stechowi is likely a junior synonym of C. roechlingi
• The Ceratosaurus vertebrae that Janensch (1920) identified as Ceratosaurus sp. are correctly IDed
• Labrosaurus meriani (Janensch 1920), based on an isolated fluted tooth from the Bern Jura, in Switzerland is referred to Ceratosaurus sp.
• Bones previously referred to Ceratosaurus from Oklahoma (Stovall, 1938) are indeterminate theropod bones at best
• Ceratosaurus sp. teeth from western Colorado are in fact correctly IDed
• Material collected by BYU at Dry Mesa, Colorado and Agate Basin, Wyoming, will be described soon and represent the largest known specimen of Ceratosaurus. As of 1999 the preparation of this specimen was complete.
• Megalosaurus ingens, sometimes referred to as Ceratosaurus ingens (Rowe and Gauthier, 1990), is too big to be Ceratosaurus
• Labrosaurus sulcatus, based on an isolated fluted tooth from the Morrison Formation of Colorado, is referred to Ceratosaurus sp.

Now some of these conclusions have held up while others have not been mentioned since 2000. Later workers, for example, don't discuss any non-North American Ceratosaurus sp. remains. There is probably a good reason for this; I will go into more detail about that on my next post. Other claims are somewhat odd (a junior synonym of a newer taxon that isn't diagnostic?). Even today, however, Madsen and Welles (2000) is the best review of all material historically assigned to Ceratosaurus.

2000 was a busy year for Ceratosaurus research. That year Brooks Britt and colleagues presented about new specimens of Ceratosaurus from Colorado, Utah, and Wyoming at the Society of Vertebrate Paleontologists annual meeting; this likely includes the material that Madsen and Welles referenced in their publication as being held at BYU. While some of this information has made its way into later publications, for the most part these specimens remain undescribed to my knowledge.

As paleontology is an evolving science, new analytical tools are always being developed. The same year that Madsen and Welles revised our view of Ceratosaurus and Britt et al. clued us in to new specimens from Wyoming, Oliver Rauhut used modern phylogenetic techniques to define Ceratosaurus as part of his Ph.D. thesis. His found the following autapomorphies (taken from Rauhut (2000) by way of Wikipedia, since I don't have access to the original thesis).

• a narrow rounded horn core centrally placed on the fused nasals
• a median oval groove on nasals behind horn core
• a premaxilla with three teeth
• premaxillary teeth with reduced extent of mesial serrations
• chevrons that are extremely long
• a pubis with a large, rounded notch underneath the obturator foramen
• small epaxial osteoderms

Some of these characters still look good 16 years later, but some of them are a bit subjective, such as, "chevrons that are extremely long." This may be due to someone simplifying what Rauhut said for Wikipedia or it may reflect the long-term trend away from relative character states. Without having Rauhut's thesis I can't really say either way.

Breaking up this wall of text with a Ceratosaurus illustration. Image by DiBgd at English Wikipedia, CC BY 2.5

Rauhut (2000) wasn't the last word on the question of, "What is Ceratosaurus?" In 2008, Matt Carrano and Scott Sampson published a revised phylogentic analysis of the ceratosaurs. Since Ceratosaurus is kind of essential to understand if you're talking about a group of animals sharing its name, they came up with another revised diagnosis.

Ceratosaur with: (1) mediolaterally narrow, rounded midline horn core on the fused nasals, (2) medial oval groove on nasals behind horn core, (3) pubis with large, rounded notch underneath the obturator foramen, (4) small median dorsal osteoderms

As time passes you can see that the subjective characters have disappeared, such as the extremely long chevrons. Others characters are now better defined. We've arrived at what is essentially the definition we are using today in 2016 when we want to refer material to Ceratosaurus. Of course you may notice that this list is pretty small, meaning that most of the skeleton can't be used to identify individual bones. Carrano and Sampson (2008) do a couple of other interesting things in regards to the history of Ceratosaurus; they restrict the use of Ceratosaurus to North America (though without discussing the African material), and explain how the Madsen and Welles (2000) taxa are junior synonyms with no unambiguous autapomorphies. So from this point onward it is generally accepted that only one species of Ceratosaurus is valid, C. nasicornis, and that the genus Ceratosaurus is found only in the Morrison Formation of western North America, a point that Carrano et al. (2012) reiterate.

Juvenile Ceratosaurus partial skeleton on display at the North American Museum of Ancient Life. Photo by Zach Tirrell, CC BY-SA 2.0

Last, and most late-breaking, is a paper out today in JVP! In this paper Carrano and Choiniere discuss the arm of the holotype of Ceratosaurus from the US National Museum. The paper stays true to its subject and redescribes the arm, something the entire skeleton is in need of, as it has undergone de-mounting and additional preparation work. They found that, as many have suspected, the hand and arm of Ceratosaurus is most similar to those of early theropod dinosaurs like Dilophosaurus, and not as closely aligned with later theropods. Even from its fellow derived ceratosaurs, the Abelisauroidea, the hand and arm appear primitive - which would make sense considering its placement relative to abelisauroids in the theropod family tree. Carrano and Choiniere (2016) also show that Ceratosaurus didn't have a useless hand either. Although small and oddly shaped compared to contemporaneous Allosaurus, the hand of Ceratosaurus was still adapted to grasp items (though not to the same extent as other theropods). The lack of any preserved claws from across the Morrison associated with Ceratosaurus skeletons makes things even more difficult; was Ceratosaurus tiny-clawed, grabbing small prey items? Or did it have huge grappling-hook slashers, ready to grab on to passing sauropods? We just don't know.

Cast of the hand of the holotype of Ceratosaurus nasicornis. Note the lack of any preserved fingers. Photo by Smokeybjb, CC BY-SA 3.0

In conclusion, how can we sum up what we know of Ceratosaurus? Well there appears to be one wide-spread but relatively uncommon (compared to Allosaurus) species of Ceratosaurus that existed in western North America during the Late Jurassic. Variation that has led to different species in the Morrison Formation being named, such as Ceratosaurus magnicornis and Ceratosaurus dentisulcatus are best explained by individual variation and changes associated with the animal's growth. Other examples of Ceratosaurus may exist outside of North America but those specimens have not been rigorously examined since 2000. Numerous teeth from across western North America, Europe, and Africa have been referred to this animal, but most workers view the non-North American specimens as not part of the Ceratosaurus hypodigm. Are these referrals sound? For that, you'll have to wait until my next post!

Works Cited

Britt, Brooks, Chure, D. J., Holtz, T. R., Jr., Miles, C. A. & Stadtman, K. L. 2000. A reanalysis of the phylogenetic affinities of Ceratosaurus (Theropoda, Dinosauria) based on new specimens from Utah, Colorado, and Wyoming. Journal of Vertebrate Paleontology 20: 32A

Carrano, Matthew T., Roger BJ Benson, and Scott D. Sampson. 2012. "The phylogeny of Tetanurae (Dinosauria: Theropoda)." Journal of Systematic Palaeontology 10.2: 211-300

Carrano, Matthew T.  & Jonah Choiniere 2016. New information on the forearm and manus of Ceratosaurus nasicornis Marsh, 1884 (Dinosauria, Theropoda), with implications for theropod forelimb evolution. Journal of Vertebrate Paleontology

Carrano, Matthew T., and Scott D. Sampson. 2008. "The phylogeny of Ceratosauria (Dinosauria: Theropoda)." Journal of Systematic Palaeontology 6.02: 183-236.

Gilmore, Charles W. 1920. Osteology of the carnivorous Dinosauria in the United States National Museum, with special reference to the genera Antrodemus (Allosaurus) and Ceratosaurus. Bulletin of the United States National Museum 110: 1–154.

Janensch, Werner. "Über Elaphrosaurus bambergi und die megalosaurier aus den Tendaguru-Schichten Deutsch-Ostafrikas." Sitzungsberichte der Gesellschaft naturforschender Freunde zu Berlin 8 (1920): 226-235.

Janensch, Werner. 1925. "Die Coelurosaurier und Theropoden der Tendaguru-Schichten Deutsch-Ostafrikas". Palaeontographica, Supplement 7 1: 1–99.

Madsen, Jim H. Jr., and Stokes, William L., 1963, New information on the Jurassic dinosaur Ceratosaurus: Geological Society of America, Special Paper 73, p. 90 (abs.)

Madsen, Jim H.; Welles, Samuel P. 2000. Ceratosaurus (Dinosauria, Theropoda): A Revised Osteology. Utah Geological Survey. pp. 1–80.

Marsh, O.C. 1884. "Principal characters of American Jurassic dinosaurs, part VIII: The order Theropoda" American Journal of Science 27(160): 329–340
Rauhut, Oliver. 2000. The interrelationships and evolution of basal theropods (Dinosauria, Saurischia). Ph.D. dissertation, Univ. Bristol [U.K.]. 440 pp

Rauhut, Oliver W. M. 2011. "Theropod dinosaurs from the Late Jurassic of Tendaguru (Tanzania)". Special Papers in Palaeontology 86: 195–239.

Rowe, T., and Jacques Gauthier. 1990. "Ceratosauria." in The Dinosauria, Weishampel, Dodson, and Osmólska, eds. University of California Press. pp. 151-168.
Stovall, J. Willis. 1938. "The Morrison of Oklahoma and its dinosaurs." The Journal of Geology: 583-600.

"Why does science have to name every little thing?"

One of the most common questions I got when I was teaching as some variation on that theme. "Why do scientists have to make things so complicated?" "Why can't they just call it something simple?" It is a question bigger than just high school level as well; one of the barriers to effective science communication and education seems to be the general "fear" of overly technical language . The general public seems to view scientists as speaking in convoluted and complex terms.

It is true that scientists have devised some very complex ways of describing things that might seem simple to a layman. And sometimes we can get wrapped up in using the terms we are familiar with when talking about our research, to the detriment of any non-technical audience. The media is also partially to blame as well, with perpetuating ideas such as all prehistoric reptiles are dinosaurs. But why do these terms exist in the first place?

This brings me to Hendrickx et al. (2015). Hendrickx and his coauthors published a paper last year breaking down theropod dinosaur teeth and analyzing many different aspects of their morphology. In addition, the authors created a standardized terminology for future paleontologists to use when describing their dinosaur teeth. Hendrickx and his coauthors explain why creating such a terminology is needed succinctly; in effect answering the question of why scientists create names for so many things.

...several pivotal theropod taxa with well-preserved dentitions still lack a thorough dental description...leading numerous authors to identify isolated theropod teeth to broad clades with uncertainty...isolated teeth are key pieces of evidence to assess vertebrate paleoecological diversity and are often used for stable isotopic studies with various applications...A better understanding of theropod anatomy and morphological variation is therefore central to help resolving systematic relationships and to provide paleoecological clues. Tooth morphology is tied to diet, which has extensive evolutionary repercussions, such as morphological convergence, more than other parts of the skeleton. Yet, theropod teeth have been shown to possess many diagnostic features of taxonomic value...Although theropod teeth seem simple at first sight, this is effectively a result of the absence of comprehensive studies on tooth anatomy and morphological variation among theropods, as well as the lack of a uniform anatomical nomenclature.

What does the wall of text mean? Basically, theropod dinosaur teeth can be used to study evolutionary relationships, paleoecology, and several other important things in paleontology, but no one has bothered to come up with a good way to talk about them.

That's the crux of scientific terminology; coming up with a good way to talk about things. Good, in this case, means usable. Terms should describe well-defined parts of an organism's anatomy. If we say, "the tip of the tooth," on a tooth that has multiple "tips", how are we to know which specific tip we're talking about? Are there differences between "wrinkles" and "grooves?"

Figure 1 from Hendrickx et al., 2015

Without understanding the distinctions between subtle anatomical differences in different taxa, how are we to find out if these features are actually taxonomically important? A quick example from the Morrison Formation. Here in western Colorado we have basically two relatively common large theropods from the Morrison: Allosaurus and Ceratosaurus. Skeletal remains of Allosaurus, including teeth, seem to dominate in the Morrison making up 3/4 of all the theropod remains (Foster, 2007). Teeth attributed to Ceratosaurus do turn up in the field, however, and are usually distinguished by the presence of ridges near their bases. Now that we have Hendrickx et al.'s paper, we can go into a bit more depth. We can say, for instance, that the teeth attributed to Ceratosaurus have basal fluting, and these flutes are not seen in the contemporaneous Allosaurus. So this may help us distinguish between these teeth in the field and keeps us from mistaking Ceratosaurus teeth (with their flutes) with wrinkled or ornamented teeth (or tooth fragments).

The description of Ceratosaurus teeth by previous authors, however, has been lacking in detail and confusing, often using different terms for the same anatomical feature. As Hendrickx et al. note, having their framework in place will help facilitate such a description and they specifically mention Ceratosaurus as being in need of such a redescription. Hopefully such a project will be forthcoming. This topic will also be the focus of my next blog post!

Going forward I am hoping to see a theropod-wide tooth catalog. While Hendrickx et al. do point out that teeth are quick to change, evolutionarily speaking, to changes in diet and feeding behavior, they also note the taxonomic utility of teeth. While many theropod teeth can't be narrowed down to a genus or species, being able to address higher-level taxonomic questions with teeth is important. In addition, some taxa appear to have diagnostic dental modifications. Doing systematic studies and descriptions of theropod teeth may yield more information on what characters are taxonomically useful and potentially add autapomorphies to established genera.

My biggest complaint is that the authors did not examine what a theropod tooth is. They identify problems with past work, the utility of teeth, and the need for a framework but there is no way to determine if this framework is applicable to a given tooth. Obviously for teeth attached to theropod jaws this isn't a problem, but the majority of the dental fossil record for archosaurs consists of isolated shed teeth. While workers in the Cretaceous and Jurassic strata have this problem to a lesser degree (though it is possible that some crocodylomorphs developed similar tooth morphologies), those of us working in the Triassic are confronted with a host of dental convergences! One need look no further than the saga of Revueltosaurus to find examples of teeth that look similar between widely divergent clades. In the Triassic there are plenty of carnivorous reptiles, many with laterally compressed teeth. While in truth the terms developed by Hendrickx et al. (2015) are likely to be broadly applicable, a brief discussion of what synapomorphies exist among the dentition of theropods would have been appreciated, so that those of us working under all that overburden could sort our rauisuchian teeth from our dinosaur teeth just a little easier.

Works Cited

Foster, John. 2007. "Allosaurus fragilis". Jurassic West: The Dinosaurs of the Morrison Formation and Their World. Bloomington, Indiana: Indiana University Press. pp. 170–176

Hendrickx, C., Mateus, O. and Araújo, R., 2015. A proposed terminology of theropod teeth (Dinosauria, Saurischia). Journal of Vertebrate Paleontology,35(5), p.e982797. 

Richard Delgado's Age of Reptiles: Ancient Egyptians

I have been a fan of Richard Delgado's Age of Reptiles series for a little while now. If you are unfamiliar with the series it is a comic that focuses on recreating the prehistoric world. Delgado has looked at the Morrison and Clovery Formations in the past with his previous volumes but it has been several years. Now he takes aim at the paleoecosystems of North Africa in the Late Cretaceous.

The cover of Issue 1. Copyright Dark Horse Comics.

 The story follows, so far, the exploits of a lone Spinosaurus as it cruises around the mangroves and deltas of what is now Egypt. The first thing that jumped out at me is that the animals in Ancient Egyptians are far more accurate than in some of his earlier works. For example:

What is happening here? Anatomy? Physiology? MAKE THEM FIGHT! Copyright Dark Horse Comics.

While the artwork has always been pleasant to downright gorgeous in previous installments of Age of Reptiles, I find the accuracy and beauty of this latest outing is commendable. I will state that I am not someone who works on Cretaceous vertebrates from North Africa, but looking at the animals and scenes presented in the first two issues of Ancient Egyptians I don't see anything that immediately jumps out at me as being horrendously wrong either paleontologically or behaviorally. I am impressed at the care that Delgado has put into portraying his animals and scenes.

Scene from Ancient Egyptians, copyright Dark Horse Comics. Holy cow, look at the difference between the earlier work and now! Blood, poop, backgrounds!

Ancient Egyptians does suffer one setback. This series doesn't fully take into account how recent work has changed our understanding of what Spinosaurus looked like. The sail is shown as one uninterrupted convex bulge. The forelimbs are long but the hind feet show three functional digits and no webbing. Both of these are contra Ibrahim et al. (2014). To his credit(?), Spinosaurus is shown on all fours multiple times...but that may not be reasonable considering it is a theropod. And Delgado does like to pronate his theropod hands.

The cover of Issue 2. Copyright Dark Horse Comics. The two back animals show pronated hands.

 Regardless, Delgado does a great job of making Spinosaurus seem alive and an actual animal, not like a monstrous killing machine (I'm looking at you Jurassic Park III). His Spinosaurus seems real. It poops. It fights. It sleeps. It fails at hunting. It hides. It tries to mate. It has the wounds to prove it.

The scarred protagonist Spinosaurus. Copyright Dark Horse Comics.

It isn't just the main character that seems real. Herbivores are violent and protective - not dumb domestic cows with scales. Mating and rearing rituals are brutal but also in line with what we know about modern animals. It may be hard to look at some of the illustrations later in Issue 2 but on the other side they are in line with what we know about how some modern adult males act in the presence of unrelated juveniles.

Issue 3 just came out at the end of last week and Issue 4 comes out in September. I am looking forward to picking them up and finishing the tale which Delgado likens to Samurai and Western classic films. The absence of narrative text might put some off but for myself I find it adds to the immersion. Where will the lone Spinosaurus find himself at the end of his journey?

The cover of Issue 3. Copyright Dark Horse Comics.

References:

Delgado, Richard. "Age of Reptiles: Ancient Egyptians" Dark Horse Comics. (2015).

Ibrahim, Nizar, Paul C. Sereno, Cristiano Dal Sasso, Simone Maganuco, Matteo Fabbri, David M. Martill, Samir Zouhri, Nathan Myhrvold, and Dawid A. Iurino. "Semiaquatic adaptations in a giant predatory dinosaur." Science 345, no. 6204 (2014): 1613-1616.

Brink et al. 2015 - What does it tell us about phytosaurs?

So new tooth news seems to be coming at a rapid pace this year! Several tooth-related papers have come out already and we're barely past the halfway mark. Most recently we have Brink et al. (2015) discussing funky features in meat-eating dinosaurs and, tangentially, other archosaurs. While I obviously love theropods and dinosaurs in general my interest at the moment is with non-dinosaurian archosaurs like our strange Chinle friends from Comb Ridge.

Duane Nash already did a good breakdown of what the article means in terms of theropod dinosaurs and how to relate the findings of Brink et al. to modern correlates as well as exploring what they could mean in terms of feeding and prey capture methods in various dinosaurs. If you haven't read his blog I'll wait.

Okay. Back? Good. As you can tell from both the article and the blog Brink et al. reject the stress-induced formation hypothesis for these interdental folds, as has been suggested previously. Instead they find that these structures are present even before stresses are placed on the teeth - while the unerupted teeth are still in the alveoli. So what does that have to do with Triassic teeth?

If you read the article you will see they sampled a few non-dinosaurian taxa (a phytosaur and an indeterminate Cretaceous croc) as well as the Triassic theropod Coelophysis. We have an abundance of phytosaur teeth at Comb Ridge and have picked up a few teeth we have tentatively IDed as theropod. So not only is Brink et al. a cool paper, it deals with some of our Triassic friends too!

Two views of phytosaur teeth in SEM and thin section, both from Brink et al. (2015), CC-BY
Image C shows mesial denticles under SEM and thin section. D shows a thin section with enamel, globular dentine, and primary dentine.

Brink et al. are looking mainly at the evolution and development of the structures with limited discussion on how the structures would have directly influenced prey capture and processing (though Nash, linked above, goes into that more). One of the more interesting things to me to come out of this is that phytosaurs have interdental fold structures like theropods and unlike crocs, Spinosaurus, ominivorous animals like Troodon and pure herbivores like ornithischian dinosaurs. Brink et al. further state that these adaptations are best interpreted as ways to capture large prey and crush bone. When we talk about phytosaurs, though, most people tend to interpret them as crocodile analogs. Sometimes this means perhaps ambushing large prey, other times preying on fish. This second option has been especially favored for the narrow-snouted forms, viewed by some as not robust enough to deal with large struggling prey.

A Redondasaurus attacks a decent sized prey item - a silesaurid. From Edyta Felcyn: go support her art!

There is some other evidence to suggest that phytosaurs were not just meekly eating fish and moderate-sized animals like dinosauromorphs (see image above). Coupled with their teeth that were perfectly adapted to ripping up large struggling prey items and mashing their bones, we have trace behavioral evidence to indicate this is exactly what happened. Last year Drumheller et al. documented a phytosaur attack on a living rauisuchian. You can read PastTime Podcast's take on the paper if you don't want to read through the paper itself. In short, though, they find evidence that a phytosaur tried to wreck shop on a rauisuchian, an animal that was basically a cross between a tyrannosaur and a crocodile. Wreck so much shop, in fact, that the phytosaur tooth went almost completely through the femur of the rauisuchian. This unfortunate fellow was then attacked by another rauisuchian and finally scavenged by a smaller phytosaur. Times were rough in the Triassic, even if you were the biggest, baddest fellow on the land.

Damaged psuedosuchian femur. The phytosaur attack is represented by the embedded tooth in Box A. Image from Drumheller et al. (2014).

If encounters like this were rare and the exception to the normal behavior of phytosaurs then the fossils described by Drumheller et al. are truly remarkable. Between the marked heterodonty found in adult phytosaurs described by Hungerbühler (2000) and the new evidence that they possessed dental adaptations that enabled them to capture, kill, and process prey larger than them it seems unlikely that this was a one-off chance encounter.

Ventral view of phytosaur snouts from Hungerbühler (2000). Note the different size and shapes of the teeth in this view.

 Instead our view of phytosaurs as fish-eaters occasionally attacking small-to-medium-sized land prey needs to be challenged. Phytosaurs were equipped with a dental battery that enabled them to routinely tackle large, dangerous, struggling prey as adults. This would include animals that were significantly larger than them. While juvenile phytosaurs seem to lack these dental adaptations (see, for example, my earlier post on this topic) and likely pursued prey smaller than themselves, adults would have been terrifying creatures to behold.

An interesting point to consider too: if phytosaurs were more like Nile Crocodiles than gharials, why don't we see ziphodont dentition in crocs? Certainly wildebeast and zebra don't give up after a fight. Brink et al. note that their Cretaceous croc also lacks ziphodont dentition, suggesting the behavior of crocs and their prey haven't changed much. Modern crocs are obviously capable of tackling large prey (though usually not larger than their own body). If they have gone hundreds of millions of years without the interdental folds and can eat large land prey, what were phytosaurs doing different?

Crocodiles and their prey in Africa - 2:57 from National Geographic

We don't have the fossils to answer that definitively but it would appear that modern crocodiles are not as good of an analogy for phytosaurs as has long been supposed. Hopefully future work at Comb Ridge and across Triassic collections will lead to new insights, clarifying what this unique clade was doing.

As an end note, Brink et al. suggest that ziphodont dentition with interdental folds is basal to all theropods, even thought phytosaurs possess the same tooth structure. It would have been nice to look at things like pseudosuchians from the Triassic to see if similar dental structure existed. If so, perhaps this sort of adaptation dates back to the rise of archosaurs in general. I guess that's another paper for another time.

Next up from me: a return to the lighter side. I'm going to be reviewing Richard Delgado's new Age of Reptiles comic series, Ancient Egyptians!

References:

Brink, K. S., Reisz, R. R., LeBlanc, A. R. H., Chang, R. S., Lee, Y. C., Chiang, C. C., ... & Evans, D. C. (2015). Developmental and evolutionary novelty in the serrated teeth of theropod dinosaurs. Scientific reports, 5.

Drumheller, S. K., Stocker, M. R., & Nesbitt, S. J. (2014). Direct evidence of trophic interactions among apex predators in the Late Triassic of western North America. Naturwissenschaften, 101(11), 975-987.

Hungerbühler, A. (2000). Heterodonty in the European phytosaur Nicrosaurus kapffi and its implications for the taxonomic utility and functional morphology of phytosaur dentitions. Journal of Vertebrate Paleontology, 20(1), 31-48.

Bigger. Badder. More teeth?

Okay, show of hands: who has seen Jurassic World? If you haven't seen it I promise this article won't be spoiler-filled. I promise I won't discuss plot points. In fact, I won't discuss anything that you can't see in the trailers. What I will discuss, though, is teeth!

So if you have seen any of the promotional material for Jurassic World you know that the scientists have created a "genetically modified hybrid" named "Indominus rex." Leaving aside issues about genetic modification and dinosaurs in the Jurassic Park universe, one of the tag lines for this new animal was "Bigger. Louder. More teeth."

Jurassic World promotional image. Image (C) Universal Studios.

Fair enough. From the trailers you know that Dr. Wu says, "She was designed to be...bigger than the T. rex." This also makes sense -Tyrannosaurus is obviously a super-cool animal and would be a big draw at an amusement park like Jurassic World. If you were setting out to make a world-beating attraction then you could do worse than to choose T. rex. While other theropods may have been larger, it is certainly the most charismatic and probably the most well known. So when they are saying that "Indominus" is bigger, louder, and has more teeth they are probably comparing her to Tyrannosaurus.

There's just one problem with that. "Indominus" doesn't have more teeth that T. rex.

Skulls of Tarbosaurus (A) and Tyrannosaurus (B) by Jørn H. Hurum and Karol Sabath [CC BY 2.0], via Wikimedia Commons

As you can see, Tyrannosaurus has a combined total of 15 premaxillary and maxillary teeth. Now let's take a look at some of the promotional images and trailer stills from Jurassic World.

All images (C) Universal Studios.

How many teeth do you see? I count between nine to 11, depending on which motion-blurred image I'm using as reference. This is a situation different from, say David Peters, because in the case of "Indominus" there is no actual skull to do tooth counts with. Unfortunately I have to make do with images.

Here is Chris Pratt under a vehicle in a still taken from a Jurassic World trailer. I have numbered the teeth in the upper jaw (that I can make out), though the depth of field and motion blur make it difficult to be certain on their ID.

So last time I checked 9 < 15. Even 11 < 15. The big, scary "Indominus" has fewer teeth than a Tyrannosaurus. Maybe they were referring to ornithomimosaurs when they were making their comparison? Who can say.

Does this really matter? No, not really. Me nit-picking the strange, croc-toothed creation from Jurassic World doesn't change anything in the grand scheme of things. I just found it amusing that one of their promo points is in fact wrong. It doesn't impact how I feel about the movie, which I enjoyed. It shouldn't change how you feel about the movie.

Want more Jurassic World teeth analysis? Join me next time here at the Prehistoric Pub when I try to figure out what the heck is going on with the "Indominus" dentition!

Tap Talk Tuesday with Dr. Phillip Manning!

It's a rainy day out in the field, so while I wait for things to dry up around here, I thought I'd post an an interview.  This interview however was from way back in 2011. The questions I asked pretty much set the standard for the questions I still ask today when interviewing.  I have tweaked them over the years, but I came up with the following series of questions because it was what I wanted to know as a kid.  The interviews I've given over the years have been wonderful. I appreciate the time that everyone has set aside to do them for me and I'm always thankful for the opportunity.  OK, let's see what it's doing outside.  I will report more soon from the field, but in the meantime, enjoy one of my first interviews below.  Until later later everyone!

For those of you who may not know, Dr. Phillip Manning is an internationally renowned paleontologist, fossil hunter and writer.  He has taught vertebrate paleontology and evolution at the Universities of Liverpool and Manchester and currently heads the Paleontology Research Group in the School of Earth, Atmospheric and Environmental Sciences (SEAES) at the University of Manchester.  Dr. Manning has published papers on many diverse subjects, including dinosaur tracks, theropod biomechanics, arthropod paleontology, vertebrate locomotion, and the evolution of flight in birds.  Along with his long list of many accomplishments that continues to grow, Dr. Manning has also worked with National Geographic on an amazing series called Jurassic CSI.  

Dr. Manning has always been a hero of mine.  On May 17, 2011, I finally got a chance to meet the good doctor in person at a lecture being given by Dr. Jack R. Horner at The Academy of Natural Sciences in Philadelphia, PA.  It was an absolute honor to meet such an educated gentleman in the field of paleontology.  I only wish that I had my copy of Grave Secrets of Dinosaurs by Dr. Manning for him to autograph.  I have fond memories of picking up this book when it first came out and never putting it down.  I highly recommend picking it up.  

Upon meeting Dr. Manning, I was a nervous wreck, but his humbleness will quickly calm you down.  He is a brilliant man, but also very down to earth.  Passionate about his work and someone I admire greatly. I appreciate him taking the time to hangout and talk with me that night.  I learned a lot.  Not long after that awesome night of meeting Dr. Manning, we exchanged e-mails.  I asked if he would be interested in doing an interview for my website and he graciously said yes!  So, without further ado ladies and gentlemen, I give you our interview.  Special thanks Dr. Phillip Manning. 

You are one of my heroes in the field of paleontology.  Who did you admire growing up?

I watched Sir David Attenborough on TV whenever I could. The series 'Life on Earth' was quite life-changing for me...I realised we lived in a big world. I have to point out, I was about 7 years old, living in a village in rural Somerset...quite the middle of no-where, but beautiful! I have been lucky enough to meet and work with Sir David on a BBC series a few years ago and he was 'the real deal', a splendid gentlemen and a scholar.

At what age did you get inspired to pursue a career in paleontology? 

When I first moved to Somerset aged about 6 or 7, I discovered I had Lower Jurassic (Lias) fossil in my own garden. That's when it started proper. However when I was aged 5, i visited the British Museum of Natural History in London, now called the Natural History Museum. Stood before me was the mount of Andrew Carnegie's Diplodocus...wow...that also had a major 96 feet impact on a very small child.

What was your favorite dinosaur growing up?  What dinosaur is your favorite now?

I had two favourites as a child, and yes...you can probably guess them both...Triceratops and T. rex. I am sooooooo grateful to have been able to find both these dinosaurs in the Hell Creek Formation now. In recent years I have grown very fond of Archaeopteryx....and hope to publish another paper on this beastie soon!

Paleontology is such a diverse field these days involving many disciplines.  What advice would you give to an aspiring paleontologist today?

My advice is simple, choose the subjects which you most enjoy, as it will be these in which you have most chance to excel. There is no single route into palaeontology, which I know is some folks chosen career path. Many of my palaeo colleagues come from both arts and science background...like myself, others are pure science and some are pure art. The key here, is I took a path that was dictated by no one. If there is a 1+1=2 path to palaeo, I'm afraid i do not know it, as thankfully we are all very different. Darwin made a point of celebrating variation within a single species :-) and we are no exception to this rule. To put it another way, there is no 'one size fits all' route for me to advise any budding bone-hunters out there. This is probably a good thing. 

However, If a person has a specific university course in mind, then I urge them to look at the entry requirements now...as this will be an affective gatekeeper after High School. If you have your heart set on being a palaeontologist, you have already taken the most important step. There are few places you can learn passion for a subject, as that is something only a few are gifted with at an early age. It seems that many such folks are also 'one' of the lucky ones.

Going to college these days and then on to grad school has become a daunting task.  Many people are unaware of how long it takes to make it to the finish line.  The rewards are great, but what would you say to someone pursuing professional studies after college?

This is a very tough question, as here I should put-on my 'professor hat' and spout the virtues University and grad school...however, like I said before...we are all very different. Some folks are terrible scientists and do not enjoy the rigours of academia, this is fine...it would be a strange world if we all ended up as 'Dr'. Some of the best field palaeontologists and great thinkers of the field did not have a formal college education. This is fine, many 'trained' academics have a tough time keeping up with 'amateur' enthusiasts. The 9 or 10 years it takes to scratch your way through 1st degree, masters and PhD can and usually is, very tough. I did it, but many do not complete their studies. I have to admit, that doing my MSc and PhD was certainly the hardest things I have done in my life.

What was or is your favorite research project?  What are some of your current projects?

Some of my favourite projects have involved digging-up dinosaurs on the Isle of Wight. I was lucky enough to help excavate the then un-named, Neovenator from the Lower Cretaceous back in 1989. It was more of a mud-bath than an excavation, as the Wessex Formation from whence it came is a tad sticky. This reminds me of my favourite joke! 'What's brown and sticky?.................a stick :-).....sorry!! My most recent projects have been involved with working on the Stanford Synchrotron, a particle accelerator than can generate super-intense x-rays that allows us to analyse the chemistry of fossils. We have mapped 120 million year old pigment patterns in Chinese fossil birds and even gotten a whiff of pigment in the famous Archaeopteryx....this work continues.

Jurassic Park was the movie I remember as a kid that fueled my passion for dinosaurs.  What was your most memorable movie?

I have to admit, Jurassic Park was quite a fun romp. I watched the UK premiere, as was studying for my Masters at the University of Manchester at the time. However, my favourite film...is not a palaeo-one, but Lord of the Rings....which I am sure will be overtaken by The Hobbit when that is released.

I remember meeting my first professional paleontologist.  Do you remember the first paleontologist you ever met?  Were you a nervous wreck?  

That's another tough question, as I was lucky enough to be taught Geology at school, so had an early intro to the field. However, when I was about about 11 years old I visited the local Museum in the ancient city of Wells (Somerset). I had some fossils that I needed identifying, as I was sure I had found a Lower Jurassic vertebra from a marine reptile....which it turned-out I had! Well's Museum is a strange little place (seemed huge to me then) and the Curator had an apartment in the Museum (strange, funny, odd, but what a great job!). I remember knocking on his door and then sitting down at a small table with my fossils finds. I honestly can't remember if I was worried or not...I think that happens when your much older. Most kids are fearless...I could do with some of that 'fearless' every now and then in my field of work.

Dinosaurs and the animals that lived at the same time as them were amazing creatures.  Why do you feel dinosaurs continue to fascinate us?

Dinosaurs are the ultimate 'safe' monsters. They are well and truly extinct, but 'monsters they be'...The sheer size and weirdness of these beasties never ceases to gob-smack me every time I see a new specimen.

What is your favorite time period?

The years from 1800 to 1860. This was an age of discovery. Here the world changed forever, from an Earth that was perceived to be 6000 years old and created by the hand of God, to an Earth of immense age inhabited by species that have evolved through the natural selective processes of 'decent with modification; into the 'endless forms most beautiful' to paraphrase good old Darwin. The foundations of 'modern geology' and the underpinning of palaeontology was also achieved in this period of time...it must have been a very exciting intellectual landscape in which to romp.

The time span in which the dinosaurs lived in was huge.  How do paleontologists remember all that information from such a vast era?  Do paleontologist focus on one particular subject?

We do not remember, those who say they do....are being economic. We use books, like anyone else, to brush-up on our knowledge as and when required. With the advent of the internet, we can now fact-check things and publish papers ever faster than before...which can be a pain in the rear sometimes, as many papers that should not be published...are!

Project Dryptosaurus has been my passion for as long as I could remember.  Why do you feel Dryptosaurus is such an important dinosaur?  

Dryptosaurus is a curious beastie in many ways. I have to be honest, I prefer Cope's name Laelaps, but this is sadly no longer valid :-( We have the lovely Tom Holtz to blame for that...thanks Tom ;-) However, we can thank Tom for bringing your beastie into the hallowed realm of the tyrannosaurs...woof! Any late Cretaceous large theropod excites folks...especially if they are the kin of T. rex. Here we have one of the worlds oldest discovered big predators from the Late Cretaceous, slap bang near some of the biggest human population centres in North America...we should know more about Dryptosaurus than T. rex!

Works Cited:

Dr.Phil Manning (School of Earth, Atmospheric and Enviormental Science - The University of Manchester). Web.10 Jan. 2012

'Tis the season for digging Triassic beasts! Part 1

Today we set out for the badlands of New Mexico and had a rather productive first day.  It was a scenic drive and as you get further out, civilization begins to disappear in your rear view mirror.  On our way, we enjoyed a wonderful geology lesson via Dr. Axel and also fancied our new field vehicle!  Yup, you heard right, we now have a new truck.  Complete with air conditioning!  Our last truck was very old and has been put out to pasture.  I will miss that suburban.  She was a good ride and I will always have fond memories of her.

Our old truck.

The new Beast!

On our way into the field.

I was up at 5AM and waited to get picked up by the good doctor.  He was there right on the tick as always and soon we were on our way to the museum to load up.  There we would meet up with the others.  Loading up the trucks is the first important thing we need to do.  You definitely don't want to forget anything or you will be up a Triassic creek without a paddle!

Getting the lab ready the night before for when we return.

The first day in the field is usually comprised of uncovering the site and getting organized.  Sometimes you have specimens in the ground that could not be taken out during the last class or field season.  That being the case, these finds need to be tended to ASAP in order to get them out safe.  After a brief lecture, we set out around the site to secure any finds that were left behind.  Specimens left behind are wrapped in plaster casts or covered with tarps to keep them safe from the harsh elements of the desert.  Along with uncovering the finds, we all have the pleasure of unloading the equipment we will be using for the time we are at the site.

Tarp covering important specimens from last field class.

The first day is mostly about prepping the site, but just by prospecting around, you can see evidence of what this area once looked like.  Fish!  Yes, fish scales, fish parts, and lots of fish fossils liter the quarry floor.  They tend to look exploded, but overall they are very beautiful to look at.  They are a perfect fossil in which to gauge what the area must of been like during the Late Triassic.

Fish fossil.  Notice the beautiful scales.

At our locality, fossils we find are sometimes found on the surface.  Trace fossils are often seen in the area.  Gretchen, our museum director, found a gorgeous example.  A trace fossil is an imprint of a specimen.  Dinosaur tracks are good examples of trace fossils.  Plants, insects, and other types of organisms can leave fossilized imprints for us to find.  Below are a few examples of burrows found in the area.  These are trace fossils that have become very prevalent in recent field seasons.

Burrows from an overturned piece of mud stone.

Gorgeous piece found by Gretchen.

You can also find bone material out on the surface at times.  While unwrapping a site we call Bravo West, Gretchen our museum director found a small bone.  Finds that are found out and about are sometimes labeled as a "Float."  Float meaning we don't know for sure where the fossil might have come from.  A good example would be a couple of turtle shell pieces I found while prospecting about.  Way above our dig site is a formation from the Pleistocene. In seasons past, large turtle shells have been found at the base of the cliff side.  Now, where is the source of these pieces?  That is yet to be discovered!

Small bone found by Gretchen while uncovering Bravo West.

Turtle shell pieces that were transported down a steep hill.

Out in the field, you sometimes encounter wildlife.  While it is rare to spot something like a wild boar or mountain lion, little creatures scamper about.  I was lucky enough to get up, close, and personal with a Collard Lizard.  He was very calm as I approached him.  Probably doesn't get many Jersey Boys bothering him, so he let my presence slide.  No spiders thank the maker!  I am terrified of Tarantulas.  Hopefully I don't encounter any this field season.

I really enjoyed our first day in the field.  Always something new and exciting to learn. I had a productive first day and so did our team!  We have a great group this year as always and we all made fantastic discoveries.  All this on the first day!  Not far from where I am currently working, the previous field team uncovered a phytosaur mandible!  It will take some time to get out, but it looks sweet!  The first thing I uncovered was a tooth.  Right under it was a vertebrae.  These two items remain as it is pouring rain outside.  The weather outside is pretty nasty at the moment.  In all my years coming out here, I have never seen the weeds so high from all the rain.  Everything I found was located several centimeters below the quarry floor.  My best find of the day was a piece of a phytosaur skull!  A decent size too!  We shall see what tomorrow brings.  

Tooth I found.

Looking good, but not the smartest field gear to wear out in the desert. This was during the cool morning.

I mentioned yesterday that I would be posting live from the field.  Well, by live I mean whenever I get a chance ha ha.  As things progress, I will be limited on time, but I will post whenever I can from out here!  Until next time, have a great night everyone.

Fossil of a fresh water clam Dr. Axel found while examining my phytosaur skull.