Tag Archives: dinosaurs

An Interview with Don Prothero

Ikonokast interviews Don Prothero.

Don Prothero is the author of just over 30 books and a gazillion scientific papers covering a wide range of topics in paleontology and skepticism. Mike Haubrich and I spoke with Don about most of these topics, including the recent history of the skeptics movement, the conflict and potentials between DNA and fossil research, extinctions and impacts, evolution in general, and the interesting projects Don is working on now.

The interview is here. Please click through and give this fascinating conversation a listen!

Dinosaurs Biting Other Dinosaurs In The Face

The number one rule of the Taphonomy Club is don’t talk about marks on bones … without placing them in context. Many marks on bones could have multiple causes, such as putative cut marks caused by stone tools on animal bones found on early hominid sites. In that case, hard sharp stony objects in the ground can cause marks that are hard to tell apart from stone tool marks. But when you find almost all the possible stone tool marks in the exact locations they would be if a hominid was butchering or defleshing the animal, then you can assert that that butchery or defleshing with stone tools was highly likely to have happened.

A similar logic has been applied by paleontologists DWE Hone and DH Tanke in their study of the fossil remains of a dinosaur from Dinosaur Provincial Park in Alberta, Canada. The dinosaur exhibits numerous bite marks, and apparently (unlike stone tool cut marks) identification of these marks as caused by carnivorous dinosaur teeth is not in question. But the location of the marks and other features allowed these scientists to argue that some sort of combat regularly occurred between members of members of the same species, or similar species, during the animal’s life. Given what is known about animal behavior and the kinds of dinosaurs around at the time, they claim that it is most likely combat between members of the same species.

The dinosaur in question is a juvenile Daspletosaurus. This is a genus of dinosaur extant in western North America between 77 and 74 million years ago (Late Cretaceous).

Since everyone knows all about Tyrannosaurus, it is helpful to compare Daspletosaurus to Tyrannosaurus. Daspletosaurus was smaller and older. Daspletosaurus ranged around 8 or 9 meters long and 2.5 tonnes, while Tyrannosaurus could be over 12 meters long and 10 tonnes. Tyrannosaurus also lived later (68 million years ago up to about the time of the great extinction). Both had short arms but Daspletosaurus’s arms were longer. Note that this kind of dinosaur, suborder Theropoda, gave rise to birds.

This particular juvenile Daspletosaurus was well preserved. Many of the bones are present, and their position in the matrix that bore them is not too far off from anatomical location. A good number of the missing bones may have actually eroded away after this part of the bone bed was exposed by erosion. There are marks on some of the bones that indicate post-death scavenging. But, most of the tooth marks are of the kind one would expect if a theropod dinosaur was biting it, and most interestingly, most of these marks show evidence of healing, and all but one mark indicating damage is on the head. Normally, theropod inflicted bite marks are found on various different bones of their prey. It appears that this individual was engaged in combat with other individuals of the same sort … other theropods. And, since this is probably the only theropod of this size at the time in the area, it is reasonable to conclude that this is evidence of infraspecific combat or competition.

From the study’s abstract:

Trace marks on the bones of non-avian dinosaurs may relate to feeding by large carnivores or as a result of combat. Here the cranium and mandible of a specimen of Daspletosaurus are described that show numerous premortem injuries with evidence of healing and these are inferred to relate primarily to intraspecific combat. In addition, postmortem damage to the mandible is indicative of late stage carcass consumption and the taphonomic context suggests that this was scavenging. These postmortem bites were delivered by a large bodied tyrannosaurid theropod and may have been a second Daspletosaurus, and thus this would be an additional record of tyrannosaurid cannibalism.

I contacted lead study author Dave Hone with a few questions and he was kind enough to give me answers.

I asked him if he had any guess as to the sex of this individual. While it is possible to sex some dinosaurs, he told me that this was not possible in this case.

I asked Dr. Hone to comment further on the suggestions that the most likely species to have inflicted the pre-mortum wounds was another Daspletosaurus, even though another similar dinosaur, Gorgosaurus, was around at the time. He told me, “We favour Daspleto for the premortem as we think (and based on previous papers) this is a more likely case with more intra than interspecifc aggression leading to these kinds of interactions,” similar to what we see in modern animals that exhibit this behavior. I also wondered if the size of the teeth could indicate the size of the offending beast, and thus confirm the species. He told me they did not look at this too closely because there are various problems with that approach. “We did look at the patterns of tooth distribution briefly but between different sizes of animals (juveniles vs adults) different sizes of teeth within the jaws (front vs back) and then things like missing teeth etc. there’s no way of separating them out. There’s just way too many variables and they are only leaving limited marks. It’s mostly hard to tell even very different animals apart from bite marks let alone two similar and close relatives like this.”

I asked how common Daspletosaurus is in the fossil record and if this was one of the more common tyrannosaurids. He told me that “Actually it’s not that common. The Albertan Tyrannosaurs are generally pretty common but we do for example have more Gorgosaurus and Albertosaurus than Daspleto,” though Daspletosaurus is well represented.

Daspletosaurus is distinct in part because of various extra bony bits in the face and around the eyes, which could be for any of a number of functions. I asked if it is possible that Daspletosaurus was more involved with usually-but-not-always non-lethal infraspecific combat than other tyrannosaurids, if these features are related to what might have been extra protection (or signaling features that might arise from sexual selection). If so, would this indicate something about social structure? He told me, “I’m very wary of making these kinds of extrapolations as some things that look like certain classic signals turn out not to be. My personal opinion is that these hornlets in various Tyrannosaurs likely did function in sociosexual signaling (at the very least I suspect they wouldn’t do much to protect the eyes since that would be tricky place to bite) but it’s hard to say much. Sociality is misleading here as some things can be very social and fight lots and others almost never and vice versa for solitary animals.”

I also wondered about how infraspecific combat square with the individual being relatively young. Would this imply it was fighting off adults intent on cannibalism? Or, were juveniles fighting it out like hyenas do (new born hyena males from the same litter engage in deadly combat)? Or fighting over food? Or engaged in ritual fighting behavior that precedes, as preparation/practice, adult fighting behavior? I wondered if this would say anything about life history development of behaviors in this dinosaur. Dr Hone told me that “it is really hard to say. This isn’t an adult, but then nor is it really a juvenile. We know that some dinosaurs at least can reproduce before they are fully grown (so they are sexually mature when they are not osteologically mature – actually rather like humans, though obviously rather unlike most mammals, and certainly birds). So things get complex fast. This animals was certainly old enough to have been fully independent (though of course they may or may not have been gregarious / social etc.). I doubt cannibalism was normal, I’m sure there were the odd fights that resulted in deaths or adults killed the odd small juvenile (just like crocs do) but it’s a rare behaviour to go after other big carnivores for food – they are rare and dangerous, so stick to baby herbivores. After that it gets even harder so I’d prefer not to speculate too much, though I’d guess that IF solitary, smaller individuals would probably not be holding territories, since they are not big enough to defend them, and obviously immature animals would not be competing for mates or breeding sites or IF in a group to be an alpha of some kind (though that’s not to rule out some aggression to maintain even a lower rank), but it’s not much to go on – just too many unknowns.

What we need, obviously, is some way to bring these creatures back to life so we can observe them alive!


Caption for the figure at the top of the post: Figure 1: Skull in right lateral view showing numerous injuries indicated with black arrows and the relevant code letter (see the text for details).

Bully for Brontosaurus

Much is being made of Brontosaurus. Brontosaurus is a genus name for a large dinosaur, known to watchers of “Land Before Time” as “Long-Necks.” That generic name dates to the 19th century, but in the early 20th century it was eliminated as a proper Linnaean term and replaced with Apatosaurus. This made us sad. Most people discover dinosaurs and learn all about a select handful of the iconic ones, including Brontosaurus, then later learn that Brontosaurs is a bogus name. And become sad.

But perhaps this sadness is all for naught, because a very recent study seems to require the resurrection of Brontosaurus (the name, not the actual beast), and that is happy, sad-killing news. Here, I’ll give you a bit of background and some thoughts on this. Don’t worry, I’m not going to tell you that you need to remain sad for some reason. In fact, I’ll argue that you never really had to be sad.

Naming Names: Apatosaurus vs. Brontosaurus

The title of this post is borrowed from Stephen Jay Gould’s essay published in his book of the same name in 1991, from which I draw quite a bit of the information for this first part.

9780393340822_p0_v1_s260x420In 1877, paleontologist O. C. Marsh published a skeletally brief description of a new genus of dinosaur found in the “Jurassic Formation” (properly called the Morrison Formation) in Colorado. He called it Apatosaurus ajax (“Notice of New Dinosaurian Reptiles from the Jurassic Formation,” American Journal of Science, 1877). Two years later, Marsh described a different find, a similar but larger dinosaur, which he named Brontosaurus (“Notice of New Jurassic Reptiles,” American Journal of Science, 1879). Both dinosaurs were quadrupedal, large, herbivorous beasts, differentiated primarily by size with Apatosaurus being about fifty feet long and Brontosaurus being about 80 feet long. (Note: The actual size of these dinosaurs varies in the literature. It will turn out that for dinosaurs, size probably matters but there is some disagreement about what exactly matters about it.)

From a public relations point of view, Brontosaurus had some advantages. It was much larger. In popular media bigness is best for a lot of things, especially dinosaurs. Brontosaurus as reported had a more complete set of bones, and it was mounted in a famous museum. (Eventually some form of it was mounted in all the famous dinosaur-focused museums that mattered, generally with that label: Brontosaurus). Marsh and others used Brontosaurus in major scientific overviews and popular commentary and reconstructions of the age. In his highly influential publication, “Dinosaurs of North America” (Sixteenth Annual Report of the US Geological Survey, 1895), Marsh penned:

The best-known genus of the Atlantosauridae is Brontosaurus, described by the writer in 1879, the type specimen being a nearly entire skeleton, by far the most complete of any of the Sauroiioda yet
discovered. It was found in the Atlantosaurus beds, near Lake Como, Wyoming, and the remains were nearly in the position in which they were left at the death of the animal. This fortunate discovery has done much to clear up many doubtful points in the structure of the whole group Sauropoda., and the species Brontosaurus excelsus may be taken as a typical form, especially especially of the family Atlantosauridae.

Marsh made the claim that Apatosaurus and Brontosaurus were separate but closely related genera. Remember that.

Decades after the initial discoveries of these extinct dinosaurs, Elmer Riggs of the Field Museum had a closer look at the accumulated material and, contributing to an emerging pattern of “lumping” species previously generated by the earlier generation of paleontological “splitters” (including Marsh), he sank Apatosaurus and Brontosaurus into one genus. He wrote, in 1903,

The genus Brontosaurus was based chiefly upon the structure of the scapula and the presence of five vertebrae in the sacrum. After examining the type specimens of these genera, and making a careful study of the unusually well-preserved specimen described in this paper, the writer is convinced that the Apatosaur specimen is merely a young animal of the form represented in the adult by the Brontosaur specimen.… In view of these facts the two genera may be regarded as synonymous. As the term “Apatosaurus” has priority, “Brontosaurus” will be regarded as a synonym.

And by “synonym” he means, sadly, extinct as a Linnaean term.

In this manner, Brontosaurus disappeared, although Brontosaurus lived on. The official genus Brontosaurs was no longer considered valid because of the rule of priority. The first name applied to a specimen is, under the rule of priority, chosen when it is discovered that more than one name is being used to describe the same genus or species. However, Brontosaurus (not italicized) managed to hang on and was widely used in museum exhibits and popular literature (both popular science and fiction), and eventually, film. One could argue that there is nothing wrong with this. A genus of dinosaur has a scientific name, but it can also have one or more popular names. The genus Apatosaurus could be said to have a couple of popular names, non-italicized “Brontosaurs” being one, another being “Long-Neck,” and maybe there are others.

But, since Brontosaurus and Brontosaurus have exactly the same spelling, one could also be concerned that science is being messed with here. The old extinct genus name should not only be set aside because of Rigg’s science, but the use of this term in any other context is an offense to rational thinking. How dare you use the term Brontosaurus! You must be a Creationist or something!

dinosaur-stamps002That problem, the fetishizing of the names, is apparently what gave Stephen Jay Gould the impetus for writing his essay Bully for Brontosaurus. He wrote the essay at the time that the United States Post Office issued its famous dinosaur stamps, which were artistic reconstructions by the famous John Gurche. I remember meeting Gurche at that time, after his stamps had been accepted for use but before they were printed, which was also about the time John was becoming famous for his Smithsonian reconstructions of early human ancestors. John had developed to an art the science of building up.

Gurche(credit Julie Prisloe)You start with a cast of a skull, then using a detailed and expert knowledge of anatomy, you add the muscle, fat, connective tissue, and eventually skin. Only the skin will be seen in the final product, even though the underlying tissues were all built with anatomical precision. The artist as anatomist does not really know in advance what the result will be, but when flesh is added in this manner to bone, the final product is arguably the best possible reconstruction that can be made. Skin color or markings and hair or fur are at that point largely conjectural, but the surface of the skin on down to the bone is based on the best available science.

Gurche’s stamps were important for several reasons. First, this was science on stamps, not a habit of the United States Post Office. Second, it was paleo-science on stamps, which is extra cool. Third, the stamps represented reconstructions of dinosaurs based on newly emerging science and method applying to both what we think dinosaurs were, and how we reconstruct extinct forms generally. Fourth, these stamps joined an all too small collection of US produced stamps that were not terribly boring to look at.

The stamps were also important for two other reasons, not quite as positive. First, the four dinosaur stamps included three dinosaurs and a Pteranodon. Pteranodons are not dinosaurs. Second, the giant sauropod (and of course there had to be a giant sauropod along with the large carnivorous thing and the roundish spiky thing, to represent the most popular groups of dinosaurs) was Apatosaurus but labeled Brontosaurus. And, yes, Brontosaurus, on the stamp, is in italics. It is not clear that this was proper Linnaean typography or just an artistic choice.

Following Gould, the first thing you need to now about the sinking of Brontosaurs into Apatosaurus is that it did not need to happen. If you troll around the Internet and read the stories about the resurrection of Brontosaurs (the name, not the beast) you will find the Rule of Priority cited again and again as the reason for that decision. But there are actually a few different “rules” that have applied to the naming of names in the Linnaean system, and Priority is only one of them. Read Gould’s essay for rich detail on this. Here I’ll just note that there is another rule that can apply: Plenary Powers. This comes into play when someone brings up a good reason (there are no rules about what the reason should be, just that it be a good one) to pick a certain name that may not have priority for a given genus or species. This is done in the plenary context of the governing body for animal names, the International Commission of Zoological Nomenclature. The commission consists of a largish number (about thirty) of zoologists. They hear the argument (much of this is done on paper) and vote. Gould cites a classic example.

The protozoan species Tetrahymena pyriforme has long been a staple for biological research, particularly on the physiology of single-celled organisms. John Corliss counted more than 1,500 papers published over a 27-year span—all using this name. However, at least ten technically valid names, entirely forgotten and unused, predate the first publication of Tetrahymena. No purpose would be served by resurrecting any of these earlier designations and suppressing the universally accepted Tetrahymena. Corliss’s petition to the commission was accepted without protest, and Tetrahymena has been officially accepted under the plenary powers.

Gould also cites the example of Boa constrictor, but I won’t cover that here. Go read the essay.

The point is, Rigg’s effort to sink Brontosaurus, presumably well intentioned and arguably appropriate, could have been overruled. But remember, Riggs reclassification happened in 1905, and while Brontosaurus as a term was well on the way to postage stamp level status, the cultural centrality of the term was probably not as well established as it would eventually become. It seems nobody came to bat for Brontosaurus. There are probably a number of reasons for that. They are probably mostly not very interesting.

The Post Office Vindicated?

Let’s look at the new study, “A specimen-level phylogenetic analysis and taxonomic revision of Diplodocidae (Dinosauria, Sauropoda)” by Emanuel Tschopp, Octávio Mateus, and Roger Benson. It was published yesterday in the journal PeerJ.

“Diplodocidae” are the Long-Necks. This Linnaean family was called the Amphicoeliidae (by Cope, Marsh’s famous rival) in 1878, and the Atlantosauridae by Marsh (Cope’s famous rival) in 1877. (The story of these family names and the dinosaurs to which they refer is rather complicated, not covered here).

The study, hundreds of pages long, looked at 81 “operational taxonomic units” (OTUs) distributed among something over a dozen probable species dating to the Late Jurassic and Early Cretaceous. The research team examined a whopping 477 features. The OTUs consist of “name-bearing type specimens previously proposed to belong to Diplodocide” and other material. This approach starts out making very few assumptions about which bones belong which species, allowing the analysis to start out with less bias than otherwise possible. This is a modern cladistic analysis. This involves measuring or observing a large number of traits that are presumed to reflect the underlying genetics, and grouping corresponding bones based on similarity or equivalence of these traits. The result is one or more cladograms that should do a good job of representing a sort of family tree of probable species. I oversimplify.

Here is the key graphic representing the Brontosaurus related results, supplied by PeerJ:

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The main result pertaining to the present discussion (though there are many other results from this important study) is that the specimens Riggs sank into one genus, thus setting aside Brontosaurus, are distinct. This requires that the term Brontosaurus be revived and applied. The iconic Long-Neck lives again (as a name, not an actual living dinosaur).

Does this vindicate Marsh and the US Post Office? As to the latter, probably not. It is highly unlikely that the US Post Office or those involved in making the Dinosaur stamps anticipated a revision of sauropod taxonomy. They were right to use the term Brontosaurus only in the way a stopped watch is right twice a day. But what about Marsh? That is a little more complicated. Marsh was working with a fraction of the material now available, and using that material, he separated Brontosaurus and Apatosaurus but did he do so correctly, based on the character differences that, if we take the new study as valid, turn out to matter?

Marsh distinguished Brontosaurus and Apatosaurus on the basis of a number of differences, but one of them was the overall robusticity of the animal, especially in the vertebrae. In “The Dinosaurs of North America” he wrote, Brontosaurus

… aside from its immense size, is distinguished by the peculiar lightness of its vertebral column, the cervical, dorsal, and sacral vertebrae all having very large cavities in their centra. The first three caudals, also, are lightened by excavations in their sides, a feature first seen in this genus, and one not observed in the other families of this group.

The recent analysis does the same. Charles Choi, writing for Scientific American and quoting the study’s lead author, notes:

“Generally, Brontosaurus can be distinguished from Apatosaurus most easily by its neck, which is higher and less wide,” says lead study author Emanuel Tschopp, a vertebrate paleontologist at the New University of Lisbon in Portugal. “So although both are very massive and robust animals, Apatosaurus is even more extreme than Brontosaurus.”

In some details, Marsh may have been a stopped watch, but clearly not the important details. The old guy got it right, we can say. Cope would probably disagree on personal grounds, of course.

The lying lizard gets its due

People seemed to care that “Brontosaurus”, the name, be preserved, which implies preference over “Apatosaurus”. But why? Does one role off the tongue more easily than the other? Is one more poetic than the other? The main reason for sadness when learning that Brontosaurus is wrong is almost certainly, as has been pointed out by many, because the term was already so much in use that it is usually learned first and nobody likes to unlearn things. But it is interesting to ask of the etymology of the terms. In another essay (or two) Stephen Jay Gould laments the demise of a different genus name, Eohippus. Eohippus means “Dawn horse” and was applied to an early horse fossil. What a great, and appropriate, name! But other remains of that same extinct form had previously been named Hyracotherium. Hyracotherium is an affront to the poetry of paleontology for three reasons, when compared to Eohippus. First, it sounds ugly. Second, it is an example of a cool name (“Dawn Horse”) being tossed out. Third, Hyracotherium is wrong. The term comes from the belief that those particular early remains were a form of hyrax, which is not a horse. Tossing out Eohippus and replacing it with Hyracotherium may have been correct by the Rule of Priority but a third rule, not previously mentioned here, could have saved the day: The Rule of Appropriateness. Hardly invoked and considered these days arcane, that rule simply stands up for a name that makes sense over a name that does not, clearly the case with the early horse.

But what about the Long-Neck in question? Gould ends his essay with these words:

Apatosaurus means “deceptive lizard” Brontosaurus means “thunder lizard” — a far, far better name… They have deceived us; we brontophiles have been outmaneuvered. Oh well, graciousness in defeat before all (every bit as important as dignity, if not an aspect thereof). I retreat, not with a bang of thunder, but with a whimper of hope that rectification may someday arise from the ashes of my stamp album.

Well said. But, in the end, not relevant. A better reference than to dignity might be to a very different aphorism, “Don’t get mad. Get even.” It took a while, but Brontosaurus is back.

For now. As great as the new study is, there are a couple of reasons that things may change again. One is our understanding of the relationship between size and form, and actually, growth in dinosaurs. It could be that some features that work to distinguish specimens cladistically are a function of change over time within a given animal, as it grows larger. This, or some other developmental or environmental effect, could knock some of the traits off the pedestal of genetic presumption, and make them invalid cladistic characters, and thus change the analysis. I mention this simply because the main features that result in bringing Brontosaurus back to life (the name, not the actual dinosaur) may be size related. Another possibility is that even though Apatosaurus and Brontosaurus are found in this study to be different, they are still close. If this research team turns out to be splitters and later on lumpers show up with more muscle, some of the now distinct taxa could be recombined, and any two closely aligned forms risk sinking, once again, into the Davy Jones’ Locker of the Linnaean system. Of course if that becomes a threat, there may be grounds, and impetus, for invoking the Plenary Rule.

I’ll end with this, somewhat tangental but I think important. The reason Gould wrote his “Bully” essay was annoyance. Gould was motivated by annoyance, by the way, in many of his popular works. He was annoyed at the way science was often portrayed in watered down form, and he was annoyed at the shallowness of the public discourse. Had he lived longer, he almost certainly would have gotten much, much more annoyed because this has become more, rather than less, of a thing because of the Internet. A simple example of this is the widespread mischaracterization of the Rule of Priority as the only thing governing resolution of naming conflicts. In the case of the “Bully” essay, Gould was annoyed at the annoyance of others with the Post Office stamps. Aping, cynically, classic conspiracy ideation, he wrote:

The Post Office has been more right than the complainers, for Uncle Sam has worked in the spirit of the plenary powers rule. Names fixed in popular usage may be validated even if older designations have technical priority. But now…Oh Lord, why didn’t I see it before! Now I suddenly grasp the secret thread behind this overt debate! It’s a plot, a dastardly plot sponsored by the apatophiles—that covert society long dedicated to gaining support for Marsh’s original name against a potential appeal to the plenary powers. They never had a prayer before. Whatever noise they made, whatever assassinations they attempted, they could never get anyone to pay attention, never disturb the tranquillity and general acceptance of Brontosaurus. But now that the Post Office has officially adopted Brontosaurus, they have found their opening. Now enough people know about Apatosaurus for the first time. Now an appeal to the plenary powers would not lead to the validation of Brontosaurus, for Apatosaurus has gained precious currency. They have won; we brontophiles have been defeated.

But more important than that, Gould underscored the importance of non-shallowness, of context, in understanding problems suffered by the likes of *Brontosaurus” (the name…), and he produced a message that in slightly modified form should go out to all those engaged in discussions of science, history, and other things, which are typically carried out on the slippery surface of very deep intellectual waters. “If you play this dangerous game in real life, remember that ignorance of context is the surest mark of a phony. If you approach me in wild lament, claiming that our postal service has mocked the deepest truth of paleontology, I will know that you have only skimmed the surface of my field.”

Pterosaurs by Mark Witton

Pterosaurs: Natural History, Evolution, Anatomy by Mark P. Witton is a coffee-table size book rich in detail and lavishly illustrated. Witton is a pterosaur expert at the School of Earh and Environmental Sciences at the University of Portsmouth. He is famous for his illustrations and his work in popular media such as the film “Walking With Dinosaurs 3D.”

The first pterosaur fossil was found in the late 18th century in the Jurassic Solnhofen Limestones, in Germany, the same excellent preservational environment that would later yield Archaeopteryx. They person who first studied it thought the elongated finger bones that we now know supported a wing served as a flipper in an amphibious creature. Not long after, the famous paleontologist George Cuvier recognized the winged nature of the beast. Witton notes that at the time, and through a good part of the 19th century, it was possible to believe that many of the odd fossils being unearthed were of species that still existed but were unknown to science. This is because most of the fossils were aquatic, and who knew what mysterious forms lurked beneath the sea? But a very large flying thing like this first pterosaur was very unlikely to still exist, unseen by European and American investigators. It had to be something major that was truly extinct. So in a way the history of extinction (the study of it, that is) was significantly shaped by this find. By the early 20th century there had been enough publication and study of pterosaurs to give them a place in paleontology, but not a lot else happened until the 1970s, when a combination of factors, including advanced technology that allowed more detailed and sophisticated study of fossils, led to much more intensive study of pterosaur anatomy and behavior.

Pterosaurs are part of the large taxonomic group that includes the lizards, dinosaurs, and birds, but they branched off within that group prior to the rise of the latter two. So, they are not dinosaurs, but cousins of dinosaurs. You can call them flying lizards, but not flying dinosaurs.

Witton explores this interesting history in some detail, and then proceeds to explore various aspects of pterosaur biology, starting with the skeleton, the soft parts (of which there is some direct but mostly indirect evidence), their flight, how they got around on the ground, and their reproductive biology. These explorations into pterosaurs in general is followed by several chapters devoted to the various groups, with a treatment of the evidence for each group, reconstructions of anatomy, locomotion in the air and on the ground, and ecology.

The resemblance of this layout to a detailed field guide for birds (or some other group) is enhanced by the use of color-coded bleeds at the top of each page, separating the book’s major sections or groups of chapters. The book ends with a consideration of the origins and endings of the “Pterosaur Empire.” It turns out that we don’t actually know why they went extinct. They lasted to the end of the Cretaceous, so going extinct along with their dinosaur cousins is a reasonable hypothesis, but they had already become somewhat rare by that time.

Pterosaurs are cool. Pterosaurs: Natural History, Evolution, Anatomy is a cool book.

Of related interest:

  • LOL Pterosaurs ….
  • Reconsidering the Reconstruction of the Pterosaur
  • Flying Dinosaurs: A New Book on the Dinosaur Bird Link
  • Giant Semiaquatic Predatory Dinosaur
  • Titanic Fearless Dinosaur Unearthed
  • Honey, I Shrunk The Dinosaurs …
  • Giant Semiaquatic Predatory Dinosaur

    It is called Spinosaurus aegyptiacus but it sounds a bit more like Godzilla. Spinosaurus is a theropod dinosaur (that’s the groups birds evolved within) found in what is now NOrth Africa, between about 112 and 97 million years ago. It was first discovered about one century ago, though those bones were destroyed during WW II. Spinosaurus aegyptiacus might be the only species of this genus, or there may be two. It is probably the largest carnivours dinosaur, up to 18 meters in length. Up top of the post is the picture from Wikipedia. Although the head looks a lot like a crock, you can see the overall Godzilla-esque body.

    A paper out today in science presents a detailed analysis of Spinosaurus aegyptiacus‘s aquatic adaptations. Writing for Science, Michael Balter notes:

    Researchers have long debated whether dinosaurs could swim, but there has been little direct evidence for aquadinos. Some tantalizing hints have appeared, however, in claimed “swim tracks” made by the bellies of dinos in Utah and oxygen isotopes indicating possible aquatic habitats in a group of dinosaurs called spinosaurs. Now, a research team working in Morocco has found the most complete skeleton yet of a giant carnivore called Spinosaurus [which] confirm that Spinosaurus was bigger than Tyrannosaurus rex, but also show that it had evolutionary adaptations—ranging from pedal-like feet to a nostril far back on the head to high bone density like that of hippos—clearly suited for swimming in lakes and rivers.

    The scientists describe Spinosaurus aegyptiacus as “semiaquatic.” It’s pelvis is small, hind limbs short, and as mentioned, its limb bones are solid to act as balast. It’s hind limbs may have acted as quasi-flippers while in water. The dorsal sail “may have been enveloped in skin that functioned primarily for display on land and in water.” They say nothing about its ability to exhale nuclear fire-breath. Perhaps that will be ascertained with further study.

    Here are some of the bones and a semi-reconstructed skeleton:

    F2.large

    Of related interest:

    <li><a href="http://scienceblogs.com/gregladen/2014/09/05/titanic-fearless-dinosaur-unearthed/">Titanic Fearless Dinosaur Unearthed</a></li>
    
    <li><a href="http://scienceblogs.com/gregladen/2014/09/03/flying-dinosaurs-a-new-book-on-the-dinosaur-bird-link/">Flying Dinosaurs: A New Book on the Dinosaur Bird Link</a></li>
    

    Titanic Fearless Dinosaur Unearthed

    I’m sure you’ve heard. The most complete skeleton of a titanosaur, a newly named species, Dreadnoughtus schrani, is being reported from Argentina.

    It is not a bird. I mention that because we’ve been talking about how birds are dinosaurs lately (see:”Honey, I shrunk the dinosaurs” and “Flying Dinosaurs: A new book on the dinosaur bird link.”).

    Dreadnoughtus schrani is a sauropod. Brontosaurus, if it existed, would be a sauropod. These are the dinosaurs with the little heads, long necks, and long tails. In cartoons they are sometimes called “long-necks.” Dreadnoughtus schrani is, as mentioned, a titanosaur, a particularly large long neck.

    How does this relate to the other dinosaurs? The dinosaurs are part of a really big group of organisms that includes crocodiles, pterosaurs (those flying things) and so on. Within this group are the proper dinosaurs which you can think of as being divided into three groups. One group is the Ornithischia, named from the greek for “birdlike.” These are not birds either, but their hips somewhat resemble bird hips. (Birds are “lizard hipped” dinosaurs, which completes the paleoirony.) The Ornithischia are separate from the other two groups which are the Sauropods and the Theropods. The Theropods include Tyrannosaurus rex and pigeons. The Sauropods includes the Brontosaurus-like dinosaurs, though of course, there is no such thing as Brontosaurus. Because people who name dinosaurs are, essentially, sadistic.

    Anyway, Dreadnoughtus schrani is estimated to have been about 26 meters (85 feet) long. So if you live in a typical city lot it could eat the bushes on your front lawn while knocking over your garage out back with its tail. It would have weighted about 59 metric tons. That’s about 65 regular tons. Nobody really knows what a ton is unless you are in certain professions, so that’s about 33 cars, or about 70 head of cattle. So, the average American could replace the usual meat in their diet with meat from one well fed Dreadnoughtus schrani for about two centuries. Give or take. This is all based on the one specimen found in Argentina. But, that individual was not full grown. So, wow. I’m not sure if Dreadnoughtus schrani is the biggest sauropod, as there are others in this size range.

    The specimen is about 45% complete as a skeleton, but about 70% of the bones in the body are represented. Unfortunately the head is missing. But really, where could it be? I’m sure they’ll find it if they keep looking!

    Titanosaurs were the major large dinos during the Mesozoic (252 – 66 mya) in the southern continents. This particular find dates to the Upper Cretaceous, the latest part of the Mesozoic.

    From the paper:
    srep06196-f2

    (A) Reconstructed skeleton and body silhouette in left lateral view with preserved elements in white. (B) Left scapula and coracoid in lateral view. (C) Sternal plates in ventral view. (D) Left forelimb (metacarpus reconstructed) in anterior view. (E) Left pelvis (ilium partially reconstructed) in lateral view. (F) Left hind limb in anterior view (metatarsus and pes partially reconstructed and reversed from right). (G) Transverse ground thin section of humeral shaft, showing heavy secondary remodelling (arrow indicates extent of dense osteon formation), a thick layer of well-vascularized fibrolamellar bone, and a lack of lines of arrested growth or an external fundamental system. Abbreviations: acet, acetabulum; acf, acromial fossa; acp, acromial process; acr, acromial ridge; ast, astragalus; cc, cnemial crest; cof, coracoid foramen; cor, coracoid; dpc, deltopectoral crest; fem, femur; fhd, femoral head; fib, fibula; flb, fibrolamellar bone; gl, glenoid; hum, humerus; il, ilium; ilp, iliac peduncle; isc, ischium; isp, ischial peduncle; lt, lateral trochanter; mtI, metatarsal I; mtII, metatarsal II; of, obturator foramen; pop, postacetabular process; prp, preacetabular process; pu, pedal ungual; pub, pubis; pup, pubic peduncle; rac, radial condyle; rad, radius; sc, scapula; scb, scapular blade; sr, secondary remodelling; tib, tibia; tpp, tuberosity on preacetabular process; ul, ulna; ulc, ulnar condyle. Scale bars equal 1?m in (A) to (F) and 1?mm in (G). (Skeletal reconstruction by L. Wright, with G. Schultz.)

    The name means “Fearless-creature guy-who-funded-expedition.” According to the authors, this is specifically where the genus name comes from:

    Dreadnought (Old English), fearing nothing; genus name alludes to the gigantic body size of the taxon (which presumably rendered healthy adult individuals nearly impervious to attack) and the predominant battleships of the early 20th century (two of which, ARA [Armada de la República Argentina] Rivadavia and ARA Moreno, were part of the Argentinean navy). Species name honours the American entrepreneur Adam Schran for his support of this research.

    For more information:

    The Scientific Report article (which appears to be Open Access): A Gigantic, Exceptionally Complete Titanosaurian Sauropod Dinosaur from Southern Patagonia, Argentina

    An open access paper on how this type of dinosaur even walked: March of the Titans: The Locomotor Capabilities of Sauropod Dinosaurs.

    Michael Balter with Science Mag: Giant dinosaur unearthed in Argentina

    Mr. Dinosaur Brian Switek: Enormous New Dinosaur as Formidable as Its Namesake Battleship

    Ian Sample at The Guardian, including a video: Battleship beast: colossal dinosaur skeleton found in southern Patagonia

    Francie Diep at Scientific American: New “Dreadnought” Dinosaur Most Complete Specimen of a Giant

    Flying Dinosaurs: A New Book on the Dinosaur Bird Link

    Flying Dinosaurs: How Fearsome Reptiles Became Birds by science writer John Pickrell is coming out in December. As you know I’ve written a lot about the bird-dinosaur thing (most recently, this: “Honey I Shrunk the Dinosaurs“) so of course this sounded very interesting to me. In a way, Pickrell’s book is a missing link, in that he writes a lot about the history of paleontology associated with the discovery, undiscovery, and rediscovery of the early bird record and the dinosaur link.

    Birds have rewritten dinosaurs. Not all dinosaurs are directly related to birds, but a large number of them are, and the features we reconstruct for them were once based on lizards, because it was thought dinosaurs were big scary lizards. Now we know many dinosaurs were big scary birds. Feathers are today a bird thing, but back in olden times — very olden times — they were probably just the normal covering for this entire category of dinosaurs (though they may have been very different). Dinosaurs were once thought of as greyish lumbering terrifying beasts. We now see them as highly active, aerobically efficient, socially dynamic, sexy (as in they had a lot of secondary sexual characteristics such as bright colors) terrifying beasts.

    Pickrell covers the history of changing thought on dinosaurs and the bird-dinosaur link. In a way , this book is about dinosaurs, focusing primarily on the bird kind. Or, it is a book about birds, focusing on their dinosaur-osity. Pickrell also goes into detail on the behavioral biology of dinosaurs reinterpreted in the context of birds.

    Pickrell’s book is well written and accessible, and thus is an excellent companion to the more scholarly literature that I know you all follow.

    John Pickrell is an award-winning science writer and the editor of Australian Geographic magazine. He has written for New Scientist, Science, Science News, and Cosmos, and won man awards.

    Greenhouse of the Dinosaurs

    You all know Don Prothero. He is an active member of the Skeptics and Science Blogging community. He is the author of several books, one of which you are totally supposed to own and if you don’t it’s kinda lame: Evolution: What the Fossils Say and Why It Matters. It occurred to me today that I never produced a formal review of one of Don’s other books that I really enjoyed: Greenhouse of the Dinosaurs: Evolution, Extinction, and the Future of Our Planet. The reason for my skipping that review is that I had a radio interview with Don during which we discussed the topic as some length.

    Despite the fact that the word “Dinosaurs” occurs in the title, this book is only partly about dinosaurs. In fact, I would say it is mostly about mammals, insofar as the critters go. And that’s good because Donald Prothero is probably the world’s leading expert on Fossil Mammals. The dinosaur part is major and interesting, though. One of the mysteries Don addresses is the presence of Dinosaurs in the region of the earth that is dark for 6 months out of the year and generally frozen. Indeed, the “greenhouse effect” was very much stronger (in that there were more greenhouse gasses) in those days than today. All that atmospheric Carbon (in the form of CO2) was eventually to be trapped in the lithosphere, which helped cause the planet to cool to the levels that were around when we, as a species (genus, really) evolved. The world in which everything alive today evolved in is a world with a few hundred parts per million of CO2 in the atmosphere, the world of the “Dino Greenhouse” had much more CO2, and we are quickly heading back to the Dinosaur era level, which is going to really mess us up.

    Greenhouse of the Dinosaurs: Evolution, Extinction, and the Future of Our Planet addresses questions of “Yeah, so, it was hot then and everything was fine, so Global Warming is not important.” Don also regales the reader with stories about doing palaeontology, about controversies in the field, and that sort of thing. And, he brings us past the K-T boundary, to the “Cainozoic” (age of “Cain) during which the earth cooled, and mammals took over to be the dominant large visible above ground life form. (Yes, yes, I know, bacteria are the dominant life form, yadda yadda… just don’t look for any murals of bacteria interacting on the wall of the Yale Peabody Musuem any time soon.)

    Greenhouse of the Dinosaurs: Evolution, Extinction, and the Future of Our Planetis a great book. Highly recommended by me.

    Extinction of the Old, Evolution of the New: What really happened to the dinosaurs?

    ResearchBlogging.orgMany years ago, a sudden event occurred that changed everything. Or at least, that is what we think now. But in truth, the event took longer than many today believe, and many of the specific details, the exact order of events, the actual meaning of each detail, are not fully understood. Indeed, in the process of describing this event today, we find considerable disagreement, or at least, it is clear that one person’s version is different than another’s. I’d be happy to give you my version of it. What qualifies me to do that? Well, for one thing, I was there when it happened…
    Continue reading Extinction of the Old, Evolution of the New: What really happened to the dinosaurs?