Why do I bother?

5 10 2007

When I was a kid, one of my most-favorite videos was the Christopher Reeve hosted documentary Dinosaur!, a program filled with shots of fossils, interviews with experts, awesome stop-motion animation sequences, and host segments shot in the dim halls of the AMNH. I haven’t seen it in years, but I remember it so fondly that it makes me want to go out and buy a VHS player just so I can watch it again. There have been more recent documentaries that have take a similar strategy, like the Jeff Goldblum-narrated When Dinosaurs Ruled series, but Dinosaur! remains my favorite, and it’s a far cry from modern programming.

“Ooo… At 8 something called ‘The Land of Lost Monsters‘ is on. Do you want to watch it?” my wife asked. I should have said “No” and saved myself the pain. The recent trend in paleo-documentaries has been to use CGI and storytelling as much as possible, pushing the actual science further and further into the background. This trend started with Walking With Dinosaurs, which was alright for what it was, but it has spawned so many clones that I wonder when we’ll be able to actually have dinosaur documentaries be about science and not just CGI critters that don’t look half as good as their big-screen equivalents (i.e. the work of Weta in King Kong [albeit speculative] and Stan Winston’s work on the Jurassic Park series). For those who haven’t had the displeasure of seeing the program, the Land of Lost Monsters is a two-hour program about man vs. beast from the time of Australopithecus africanus to the Pleistocene. Rather than containing any educational content, the show is all about sensationalism, hominids being beset by ravenous monsters throughout history. The treatment of Neanderthals as only cold-loving super-hunters that craved mammoth flesh was enough to make me roll my eyes, and the analogy “Neanderthals were to humans what the saber-tooth tiger was to a housecat” was enough to make me change stations.

What is strange about the current trend in pseudo-scientific television programming is that there are some people who still realize how to make a good documentary, even if it’s not prominently shown on the air. For instance, I didn’t particularly care for Walking With Prehistoric Beasts, but a companion documentary about the science behind the show (featuring interviews with many paleontologists) was fantastic. Likewise, the series Dinosaur Planet featured little “science breaks” here and there giving the audience some clue as what evidence the reconstructions were based upon. The interruptions were far from comprehensive, but there was at least the recognition that scientific reality should be addressed. I won’t go into the Nigel Marvin Chased by… and Prehistoric Park nonsense as I don’t want to go sailing off on a more vicious rant than necessary here.

At this point I should probably mention why I torture myself with shows I know are just going to be repackaged sensationalism with little scientific content. While I am trying to educate myself more and more about the scientific points of paleontology, I also am very much interested in the public perception of dinosaurs and other prehistoric creatures in paintings, drawings, sculpture, television, movies, amusement park rides, etc. All contribute (not always helpfully) to the public understanding of creatures that are no longer around to be viewed, at least not with flesh on. When someone creates a 3-D model of a Tyrannosaurus I am curious as to what it will look like, how it will move, what behavior the producers will make it perform, etc., and I am very concerned with the move towards “edutainment” on many of the “science” networks like TLC, the Discovery Channel, and the National Geographic Channel. Good programming is seemingly few and far between or generally less-promoted than the expensive rubbish that is constantly generated, a good documentary on the juvenile Tyrannosaurus “Jane” and a stunning documentary about lions & buffalo in Botswana (Relentless Enemies, to which there’s a beautiful companion book) receiving much less attention than pure B.S. about Bigfoot and “Hogzilla.”

To sum things up a bit, I feel that current paleo-programming all-too-often cheats the audience by hiding the science (or even distorting it), making it appear that all the problems have been solved and we now know everything about these animals. Documentaries that are supposed to be educational are more like B-grade monster movies, only they’re not nearly as fun to watch. As discussed in the comments of The Ethical Palaeontologist as well, many spectacular paleontological finds that are being published in Nature or Science seem to be little more than brief announcements, and it can only be hoped that the specimens will be more fully studied and described (as is the case with the strange theropod Majungatholus from a few years back). Perhaps I could use these problems as a way to launch into the whole “framing” issue, but I think I’ll leave that sleeping canid lie for the moment, although misrepresentation or oversimplification of paleontology to the public is nothing new.

This post shouldn’t be taken as a cranky call to return to some of the methods of paleo-documentaries of the 80’s and 90’s, however, even though I wonder what a modern day equivalent of “Mesozoic Mind” would look like (hat-tip to Neil for unearthing the video);

And while we’re at it, here’s another video that’ll probably bring back memories for some readers, and see this previous post for even more;





Dino News that I don’t have time to blog about (yet)

4 10 2007

So many fossils, so little time. Luckily the blogosphere is abuzz with paleo-nerds like myself, and there’s been plenty to talk about (especially since this is conference season). My ethical palaeontologist friend Julia has got the scoop about the new hadrosaur Gryposaurus monumentensi (as well as some good commentary about the quality of the new paper about the dinosaur vs. dinosaur “announcements” in Science and Nature), and the all-star team of Darren Naish, Matt Wedel, and Mike P. Taylor has launched a new blog called SV-POW!, featuring plenty of pictures and easy-to-understand descriptions of some of the most amazing structures ever evolved by vertebrates. Matt from the HMNH also wraps up his Synder Quarry series this week (if you haven’t been reading it, you’ve been missing out), complete with some great illustrations of phytosaurs. I’d love to write more about Gryposaurus monumentensi, but I’d be lying if I said my knowledge of ornithischians was even close to adequate to give it the treatment it deserves (plus, I still owe you all my Tyrannosaurus, juvenile sauropod, and Cretaceous N.J. posts). Still, check out the links; there seem to be a growing number of paleo folks running blogs, and I think that’s definitely something to be happy about.





The shape of things to come

28 09 2007

I was hoping to have my sauropod post finished this afternoon, but much like the giants themselves over the course of evolution, it just keeps getting bigger. A post that I initially intended to be about juvenile specimens that had been found has turned into a larger discussion of behavior, physiology, and other matters dealing with how the animals lived, and I’m hoping that I can present an interesting and accurate end-product soon. Until then, however, here’s a picture of a juvenile Barosaurus mount from the AMNH;

Juvenile Barosaurus

It’s a little blurry (sorry) but the differences between it and adult sauropods are striking, and there is just so much to talk about that I should probably stop myself before I spoil too much of the upcoming work.





Friday Morning Notes

28 09 2007

The amount of reading I normally am able to get accomplished has suffered greatly this week; I’ve read bits and pieces of a few different books but I haven’t been able to rip through works at my usual pace. This is probably just as well, however, as many of the books I was reading were more important to me in a historical sense (understanding what scientists thought about paleontology in the past), and most of the information was already familiar. Then, yesterday afternoon, Phil Currie/Kevin Padian’s Encyclopedia of Dinosaurs arrived, and it’s proven to be a very refreshing read. As is apparent to many readers of this blog, I definitely need to work on my anatomical understanding of dinosaurs (and tetrapods in general), and I have been learning a lot from what I was able to read last night (I read all the entries for “A” and “B”). Some of the entries are fairly technical and proved how much I still have to learn (like Currie’s entry on braincases), but others were more plainly written and I had a lot of “Aha! So that’s what that is” sort of moments. Such an entry was John Hutchinson and Kevin Padian’s entry for the clade Arctometatarsalia, and I definitely came away that entry with a more refined understanding of the arrangement of metatarsals and ankles in theropods. Spencer Lucas’ entry on Biostratigraphy was also very helpful, and so clearly written that I think nearly any reader would be able to understand it.

Given that the book is a amalgamation of work from various researchers and authorities, some entries are a little better than others, although so far I don’t have much to complain about. I know the book is a little dated (1997), but I’ve tried to keep recent changes I know of in mind as I read along. Although I am learning more about anatomy slowly but surely, I know that I’m now at the point where I really do have to get a textbook or other resource on skeletal anatomy (and I’m still waiting for the day when I can afford to purchase Romer’s Osteology of the Reptiles). Still, as I noted before, it’s refreshing to dive into a more technical scientific work and be able to get something out of it, and even though it might seem like a Herculean task I’m going to try and read the encyclopedia from cover-to-cover. After that I’ll probably take a “break” with something shorter, but I also want to try and read the whole of the 2nd edition of The Dinosauria, being that I’ve only been referring to it now and again when necessary. Once I’ve been able to do those maybe I’ll be able to move on to Gould’s 2,000+ page The Structure of Evolutionary Theory, but that might have to wait until winter break. Of course I’m saying all this now, not knowing what my life will be like in the coming weeks and months, but I think that I can do it (and I think I’ll greatly benefit from such an undertaking). The more I learn, the more I get sucked in, and I’m trying to teach myself as best as I possibly can.

I’ll be away for much of this weekend as well, my wife’s birthing falling on the 30th, and her chosen activity being camping up in New York. I’ll still write today and on Sunday when I get back, but on Saturday I belong to Tracey. There will still be plenty to enjoy in terms of paleo-blogging, however, with The Boneyard coming up at Fish Feet tomorrow, although I’m hoping my recent reading will help me in construction a better juvenile sauropod post when I get back.





Of feathers, nests, and dinosaurs

24 09 2007

In 2006, researchers Peter Dodson and Steve Wang estimated that perhaps 71% of all the dinosaur genera that ever existed have yet to be discovered, with majority of the genera that we are likely to find potentially being described within the next 100 years. Whether the estimates are correct or not, there can be little doubt that we are in a “Golden Age of Paleontology” (as far as dinosaurs are concerned, at least), the known diversity of dinosaurs increasing at a prodigious rate. While the majority of the as-yet-unknown dinosaurs are still in the ground, we should not forget that the dusty storage rooms of museums and universities can hold startling fossils, too, as paleontological expeditions often collect more than can be carefully studied and described by the scientists. While not a dinosaur, the discovery of the archosaur Effigia okeeffeae from Ghost Ranch, New Mexico in storage at the American Museum of Natural History, has opened many new lines of inquiry for scientists interested in the Triassic. Not all such forgotten fossils need to represent wholly new groups of animals to be significant, however.

It has often been remarked that if the famous specimens of Archaeopteryx from the lagerstatten of Bavaria did not preserve feather impressions, they would have been deigned small theropod dinosaurs (T.H. Huxley was, as far as I am aware, the first to do this, although I do not have the precise quotation at hand). It isn’t surprising, therefore, that this actually occurred several times, the urvogel turning up again in unexpected places. One of the first to come to light was the Teyler specimen, initially discovered in 1855 (five years prior to the discovery of the single feather described in 1861 by Christian Erich Hermann von Meyer). Labeled Pterodactylus crassipes, the fossil would remain “hidden in plain sight” on display in the Teyler Museum in the Netherlands until John Ostrom correctly identified the fossil in 1970. While possibly only a footnote to the larger story, Ostrom’s discovery created a taxonomy problem as well; because the Teyler specimen was older, traditionally the species name crassipes would have priority over lithographica (Pterodactylus obviously not applying because Archaeopteryx was not a pterodactyl). The name Archaeopteryx lithographica had been used prominently in the literature for over 100 years, however, and so (thankfully) the species name of the early bird remained lithographica.

Eichstatt specimen
A replica of the Eichstatt specimen of Archaeopteryx, on display at the AMNH.

After Ostrom’s find, other specimens started to appear, often confused with the dinosaur Compsognathus, also known from the Solnhofen limestone of Germany. In 1973 F.X. Mayr discovered what is now known as the Eichstatt specimen, which he sent to Peter Wellenhofer in order to confirm its true identity. Later, in 1988, Wellenhofer himself discovered another specimen that had been labeled Compsognathus in the collection of the former mayor of Solnhofen, and Wellenhofer again ran into Archaeopteryx in 1992 when a smaller specimen came out of the Solnhofen limestone.

Archaeopteryx
Gerhard Heilmann’s exquisite illustration of the Berlin Archaeopteryx from his work The Origin of Birds.

Such confusion between Compsognathus and Archaeopteryx show the importance of careful examination and taphonomy to paleontology, however; the chief reason why several specimens were misidentified was due to their lack of feather impressions. The exquisite preservation that makes the Berlin specimen of Archaeopteryx a work of natural art is even rarer than the collected remains of the genus itself, and a simple matter of burial environment can seemingly make all the difference. Indeed, in an age where feathered dinosaurs continue to astonish scientists and the public alike, the presence of absence of feathers on larger animals can be problematic. While smaller dinosaurs like Sinosauropteryx and early birds like Confusciusornis are often found preserved in ash falls that allow their discoverers to make out their feather coverings, larger animals may not be covered up as quickly or have such fine detail preserved, as seen from the partial skeleton of Gigantoraptor described in Nature earlier this year. While it is not unreasonable to infer that the giant Oviraptor-like dinosaur had feathers covering its body for at least some of it’s life based upon its relationships to known feathered dinosaurs, no hard evidence of feathers was found, so what sort of feathers it had, how much of its body was covered, and other details remain (for the time being) largely unanswerable. In fact, feather impressions associated with Gigantoraptor may never be found, but some new research involving it’s cousin Velociraptor may provide some clues as to whether the large oviraptorid had plumage or not.

The medium-sized theropod Velociraptor was discovered during the famous American Museum of Natural History expeditions led by Roy Chapman Andrews to the “Flaming Cliffs” of Mongolia during the early 1920’s, and the first remains of Velociraptor to be examined gave the researchers the impression that it was capable of catching relatively large, quick prey with its hands. While certainly an impressive dinosaur, Velociraptor was not as popular as it’s dromeosaur relative Deinonychus, although Gregory S. Paul’s popular book Predatory Dinosaurs of the World started the ball rolling to get Velociraptor to be a household name. While Paul’s book was insightful and prescient in many ways (including its depictions of feathered dinosaurs), the taxonomy in the work was a bit strange, lumping Deinonychus under the genus Velociraptor. This wouldn’t have been of much ultimate consequence, except the book was timed just right to have an important influence on Michael Crichton while we wrote the best-selling novel Jurassic Park, the name Velociraptor being attributed to Deinonychus. This tradition was carried on in the blockbuster film adaptation and in two sequels, the name Velociraptor overshadowing Deinonychus in prestige. As mentioned previously, however, despite the taxonomic reshuffling Paul’s book was important as it drove home the evolutionary relationship between dinosaurs and birds, and in recent years many dinosaurs have come out of Asia showing that they were covered in feathers.


The skull of Velociraptor. From Osborn, H.F., et al. “Three new Theropoda, Protoceratops zone, central Mongolia.” American Museum novitates ; no. 144. 1924

So, how can we tell if dinosaurs that were not find with associated feather impressions had feathers or not? Until now, feathers are often implied for dromeosaurs during at least some stage of life due to evolutionary relationships, but a new (albeit short) paper by Alan Turner, Peter Makovicky, and Mark Norell shows that there are osteological features that tell of the presence of feathers. Along the ulna of a Velociraptor specimen from Mongolia, 14 bumps about 4mm apart were found in a straight line along the bone, directly corresponding to the same structures in living birds, the bumps serving as an anchor for the secondary feathers. This is an amazing find, especially since Velociraptor shows the presence of actual feathers, not just the “fuzz” or integumentary fibers seen on related dinosaurs like Sinosauropteryx. I have to admit that I chuckled a little when I saw one reproduction of Velociraptor covered in feathers, arms obscured by secondaries, but now it seems that such a reconstruction is much closer to the truth than the traditional leathery-skinned model. While the authors of the paper do note that some dinosaurs could have had feathers while the secondary feather anchors were absent, the presence of such a trait gives us a new feature of the bone that can be used to determine whether a dinosaur had feathers or not, and I hope a larger re-investigation of the ulnas of dromeosaurs will be undertaken as it could help determine the presence of feathers on species too big to have them properly preserved.

Quill Comparison
The anchors for the secondary feathers in Velociraptor and a Turkey Vulture. From Turner AH, Makovicky PJ, Norell MA (2007) “Feather Quill Knobs in the Dinosaur Velociraptor.” Science 317(5845):1721.

Still, the question of what was Velociraptor doing with secondary feathers remains. It had previously seemed plausible that many of the non-avian dromeosaurs could have lost some of their feathery coverings, possibly only being covered with feathers as a juvenile. This fossil refutes such a notion for Velociraptor, at least, and secondary feathers could have had any number of uses. While they likely didn’t help much in terms of an individual dinosaur’s thermoregulation, they could have been used for signaling/communication, sexual selection, or been used in the temperature regulation of nests. Personally, I think all these factors could have played a role to a greater or lesser extent, but it is the nest hypothesis that interests me the most.

Troodon nest
A non-feathered reconstruction of Troodon on a nest. From Horner, J.R. “Dinosaur Reproduction and Parenting.Annu. Rev. Earth Planet. Sci. 2000. 28:19–45

Those who know their paleo-history will recall that Velociraptor was not the only new theropod to be discovered by Roy Chapman Andrews and his crew. Oviraptor was also uncovered during the expeditions, and the presence of the dinosaur in association with some of the first-known dinosaur eggs gave paleontologists the impression that the theropod was stealing the eggs (hence the name Oviraptor).

Oviraptor nest
An oviraptorid theropod in a brooding position over a nest. From Clark, J.M., Norell, M.A., and Chiappe, L.M. “An oviraptorid skeleton from the late Cretaceous of Ukhaa Tolgod, Mongolia, preserved in an avianlike brooding position over an oviraptorid nest.” 1999. American Museum novitates ; no. 3265

Such an interpretation was not to last, however. Research by AMNH staff during the 1990’s showed that the “Protoceratops” eggs that H.F. Osborn and other scientists thought Oviraptor was stealing were really Oviraptor eggs to begin with, the embryo of one of the tiny theropods being preserved inside and allowing for identification of certain eggs with a particular variety of dinosaur. This relationship was further strengthened by the analysis of an oviraptorid dinosaur, probably Oviraptor, in a brooding position on top of a nest. The preservation of this specimen indicates that it died on top of the nest and was not deposited on it after being moved from elsewhere, there being little disturbance to the nest and parent overall. While the discovery of such behavior is momentous in and of itself, if we apply the discovery of secondary feathers in Velociraptor to the oviraptorid (a close evolutionary relative) it would seem that the dinosaur was shielding the eggs with the hypothetical feathers. This is still conjectural, and the oviraptorid would have to be closely investigated to determine whether it had secondary feathers or not, but I don’t think it’s out of the question to infer that, should this oviraptorid be found to have secondary feathers, it was fanning them out over its eggs when it died.

Oviraptor Nest
An oviraptorid sitting on a nest, reconstructed as Citipati. From Clark, J.M., Norell, M.A., and Chiappe, L.M. “An oviraptorid skeleton from the late Cretaceous of Ukhaa Tolgod, Mongolia, preserved in an avianlike brooding position over an oviraptorid nest.” 1999. American Museum novitates ; no. 3265

Given such bird-like behavior in the oviraptorids, it may come as a surprise to find that non-avian theropod dinosaurs may not have had a reproductive cycle like that of modern birds. In a paper released earlier this year, Gregory M. Erickson and others determined that four oviraptorids and one Troodon-like theropod studied seemed to show a more reptilian mode of growth, in that sexual maturity was reached as growth slowed down. This differs from the reproductive modus operandi of living birds, which grow to full size long before breeding begins. While it seems that the dinosaurs, like living crocodiles, took more than a year to reach adult size but attained sexual maturity as adult size was achieved, living birds show explosive growth rates that allow them to reach adult size in much less than a year, yet they are not sexually mature for some time afterwards. Indeed, in dinosaurs it seems sexual maturity was size-linked, while in birds this relationship was decoupled.

Oviraptor Nest
On oviraptorid, Citipati, on top of a nest. From Erickson, G.M. et al. “Growth patterns in brooding dinosaurs reveals the timing of sexual maturity in non-avian dinosaurs and genesis of the avian condition.Biology Letters Volume 3, Number 5. October 22, 2007

Despite the difference in growth patterns and life cycles, it is starkly apparent that birds evolved from theropod dinosaurs, some of their closest relatives being the dromeosaurids like Velociraptor. The “big idea” of a evolutionary relationship between dinosaurs and birds has been firmly established, but there are many questions that have yet to be resolved. Helping to further clarify the picture of bird evolution, another recent paper by Alan Turner, et al. (also appearing in Science) describes the new dinosaur Mahakala
omnogovae
, which shares a number of features with birds but not later dromeosaurs.


Dromeosaur Phylogeny

Phylogenetic tree of Paraves, taking temporal factors into account and reflecting changes in body size (click for larger image). From Turner, A.H. et al. “A Basal Dromaeosaurid and Size Evolution Preceding Avian FlightScience 317, 1378 (2007)

What is surprising about Mahakala is its mix of features and it’s small size. For some time one of the big questions of bird evolution has been “Why did relatively large dinosaurs shrink to take wing?” I had always felt that this was putting the cart before the horse a bit, but now Mahakala has offered up fossil evidence that the large size seen in later dromeosaur celebrities like Velociraptor is a derived condition, the common ancestor probably being no larger than Archaeopteryx.

What does trouble me about this find is it’s age; Mahakala is Campanian (83.5-70 mya) in age. As made clear by the temporal arrangement of the phylogenetic tree, this makes Mahakala much older than Archaeopteryx, Confuciusornis, Yixanornis, and other birds. While Mahakala can tell us much about evolutionary history and has shown that troodontids and dromeosaurids shared a common ancestor which in turn shared a common ancestor with birds (helping to explain those nice secondary feather characteristics in Velociraptor), I am more anxious to see if older, Jurassic relatives can be found. The dinosaurs coming out of Mongolia and China are fantastic finds, but I still find the time disparity between Archaeopteryx and its Cretaceous cousins to be irksome. I’m not the first to bring up such issues either, and I have to say that I do agree with the perspective of Peter Dodson; we need to look at the “big picture” if we’re going to figure this out. In a paper entitled “Origin of Birds: The Final Solution?” Dodson writes;

A philosophy of critical realism seems more congenial for analysis of evolutionary biological individuals having a real history [than cladistics alone]. Cladistics uses parsimony as a first principle, which may be rejected on the grounds that nature is prodigal in every regard. Parsimony based on morphology suffices only when there are no other data sets to consider. Cladistics systematically excludes data from stratigraphy, embryology, ecology, and biogeography that could otherwise be employed to bring maximum evolutionary coherence to biological data. Darwin would have convinced no one if he had been so restrictive in his theory of evolution. The current cladistic analysis of bird origins posits a series of outgroups to birds that postdate the earliest bird by up to 80 million years. This diverts attention from the search for real bird ancestors. A more coherent analysis would concentrate the search for real avian ancestors in the Late Jurassic.

As Dodson notes, morphological analysis alone is not going to get the job done, although I was much relieved by the fact that Turner, et al. used a time scale in constructing their tree. Especially concerning birds, I had always wondered why I would occasionally see animations of Deinonychus growing feathers and flying away as a Canada Goose when Arcaheopteryx was much older. It should be noted that Archaeopteryx is the oldest known bird, not necessarily ancestral to all later birds, but I would hope that more focus would be given to the Jurassic in the search for bird origins as I think the most important fossils to the origins of birds are far older than Mahakala. The chief problem with uncovering the most distant past, however, is that factors of taphonomy might inhibit identification of early bird relatives, especially if they are not preserved in lagerstatten deposits. The fine preservation of so many feathered dinosaurs are partially what has made them so popular, and unless fossil beds resulting from ash falls or ancient lagoons are found, the search for the “early birds” may prove to be exceedingly difficult.

The fossil finds recently reported in Science and elsewhere are definitely important, especially since they shed new light on the evolution of birds and of their dinosaurian relatives. Some, however, have greeted the recent studies with groans; hasn’t everyone had enough of feathered dinosaurs? Such attitudes are unfortunate, as there is still much to learn from specimens that have already been known for a long time. Constant revision and careful reanalysis are the bread-and-butter of good science, and I don’t think any generation of workers should be content with saying “It’s been done” and assume that everything they’ve been told previously is still true. This is not a call to develop new hare-brained hypotheses for their own sake, but rather a plea to keep going back to the dusty shelves of museum basements, to take another look at structures that were initially described decades ago, and to try and keep the bigger evolutionary picture in mind in the search for new specimens. There is too much to learn for any one person to take on these tasks on their own, but as a community I think scientists can still make old bones give up new secrets.

References;

Clark, J.M., Norell, M.A., and Chiappe, L.M. “An oviraptorid skeleton from the late Cretaceous of Ukhaa Tolgod, Mongolia, preserved in an avianlike brooding position over an oviraptorid nest.” 1999. American Museum novitates ; no. 3265

Dodson, P. “Origin of Birds: The Final Solution?American Zoologist. Volume 40, Issue 4 (August 2000)

Erickson, G.M. et al. “Growth patterns in brooding dinosaurs reveals the timing of sexual maturity in non-avian dinosaurs and genesis of the avian condition.Biology Letters Volume 3, Number 5. October 22, 2007

Horner, J.R. “Dinosaur Reproduction and Parenting.Annu. Rev. Earth Planet. Sci. 2000. 28:19–45

Nesbitt, S. “The Anatomy of Effigia okeeffeae (Archosauria, Suchia), Theropod-Like Convergence, and the Distribution of Related Taxa.Bulletin of the American Museum of Natural History. Number 302, Issue 1 (January 2007)

Osborn, H.F., et al. “Three new Theropoda, Protoceratops zone, central Mongolia.” American Museum novitates ; no. 144. 1924

Paul, G.S. Predatory Dinosaurs of the World. Simon & Schuster, NY. 1988

Shipman, Pat. Taking Wing. Touchstone, NY. 1998

Turner AH, Makovicky PJ, Norell MA (2007) “Feather Quill Knobs in the Dinosaur Velociraptor.” Science 317(5845):1721.

Turner, A.H. et al. “A Basal Dromaeosaurid and Size Evolution Preceding Avian FlightScience 317, 1378 (2007)

Wang, S.C., and Dodson, P. “Estimating the diversity of dinosaurs” PNAS. September 12, 2006, vol. 103 no. 37 13601-13605





Photos from the AMNH (yet again)

22 09 2007

Here are a few of the photos I took today during my visit to the AMNH. I decided to be “adventurous” and take exclusively B&W shots, hoping to better convey the mood of some of the fossils (or their replicas) that I was looking at. I’ll leave you to be the judge as to whether any of them succeeded in giving more life to the old bones than I have been able to do with color photography.

Allosaurus
The relatively gracile (at least compared to the specimen on the 4th floor, see below), yet dynamic mount of Allosaurus in the Grand Rotunda of the AMNH.

Allosaurus
The skull of the 4th floor Allosaurus, the famous mount being bent over the chewed vertebral column of an Apatosaurus.

Skull
Skull of the “Bear Dog” Amphicyon, a member of the Carnivora from the 4th floor mammal halls. Notice the big saggital crest, the placement of the cheekbones further out from the head, and lack of bone that (while typically not closed at the back) would normally surround the eye. This creature would have had an incredibly powerful bite.

Hyaenodon
Indeed, the skull of Amphicyon reminded me of that of the creodont Hyaenodon. Again, notice the sagittal crest, the cheekbones placed further out from the skull, and the near lack of bone that would enclose the eye. While smaller than the “Bear Dog,” I still wouldn’t want to cross a Hyaenodon on a bad day.

Hoplophoneus
Compare both those skulls with that of the nimravid Hoplophoneus and you’ll see what I mean. Hoplophoneus doesn’t have as prominent a sagittal crest, and although it still seemed to have large jaw muscles, there isn’t the same degree of reduction of bone surrounding the eye as is seen in the previous two mammals.

Smilodon
And, if you like, you can compare them further still with this Smilodon that had broken off it’s left canine. Such occurrences were likely painful, debilitating, and possibly even eventually fatal, and it makes me wonder if this one died as a result of it’s wound or if it continued to survive for some time longer (which opens up all sorts of questions).

Smilodon
A close-up of a more intact Smilodon.

Giant Anteater
A stuffed Giant Anteater from the Hall of Biodiversity. I much prefer photographing lives xenarthrans, however.

Apatosaurus
Apatosaurus is the first sight to grace visitors entering the Hall of Saurischian Dinosaurs.

Apatosaurus
The robust neck of Apatosaurus looms high above.

Apatosaurus print
Casts of the sauropod footprints R.T. Bird found in Paluxy, TX.

Apatosaurus
Apatosaurus from the rear.

Barosaurus
The head of Barosaurus, held up to (perhaps literally) dizzying heights.

Barosaurus foot
One of the forelimbs of Barosaurus, held out threateningly at the Allosaurus in the first photo.

Barosaurus
The head of a mini-reconstruction of Barosaurus.

Stegosaurus
The juvenile Stegosaurus model was pretty impressive, too.

Camarasaurus
A skull of Camarasaurus.

Biosphere
One of the largest self-contained “bioshpheres” I have ever seen. The little dots are shrimp.

Corythosaurus
One of the most wonderfully preserved (and in my opinion, publicly unappreciated) skeletons every found; a complete and articulated Corythosaurus with skin impressions, collected from the Red Deer River region of Canada.

Corythosaurus
A juvenile hadrosaur, probably either Corythosaurus or Lambeosaurus. I ran back and forth looking at skulls to try and figure it out, but the skull of the juvenile is slightly distorted, so (me being without access and a CAT scan at hand) I wasn’t able to confirm or deny my leaning towards my hypothesis of it being a Corythosaurus.

Deinonychus
A reconstruction of a Deinonychus skull. I looked at the forearms of the skeleton for signs of feather attachments (as had just been announced for Velociraptor by AMNH scientists) but I couldn’t see any, nor could I get close enough to get a good look.

Pigeon
Outside, one of it’s distant, extant relatives took a sip from a small puddle.

Edaphosaurus
The skull of the synapsid Edaphosaurus.

Elasmosaurus
The toothy jaws of Elasmosaurus.

Giant Squid
The famous Giant Squid that spreads its tentacles above the Hall of Biodiversity.

Gorgosaurus
The skull of Gorgosaurus, formerly Albertosaurus (although this specimen was first introduced to me as Gorgosaurus in the first place…)

Meteor
Perspective on a large, iron meteorite.

Pretosuchus
One of my most favorite mounts in the entire museum; Prestosuchus.

Triceratops
A close-up of Triceratops.

Tyrannosaurus
The most popular dinosaur in the museum, Tyrannosaurus rex.

Tyrannosaurus
The crushing jaws of Tyrannosaurus.

Leopard
A stuffed Leopard, posed over a peacock. This is another animal I would much rather photograph while living.

Charlotte
And last but not least, my little cat Charlotte, silhouetted against the evening light while she watched the birds outside.





Prehistoric Flashback…

21 09 2007

Many years ago, I can’t remember exactly when, I spent the majority of a wonderful Thanksgiving Day watching a marathon of dinosaur documentaries on PBS. I do not remember what the series was called, I don’t remember how many of episodes there were, nor do I remember the year they were aired, but I do remember the dinosaur animation. Someone has been kind enough to put some of the paleo-vignettes up on YouTube and it’s definitely a bittersweet experience seeing them again. One the one hand, I loved the show as a kid (my parents had to tear me away from it so the annual consumption of the dino-descendant carcass could begin), but seeing them now nearly resulted on me rolling on the floor laughing. I won’t specifically go into what’s wrong with each of these videos (at least not yet), but it seems to me that the dinosaurs are both new and very old. They’re not waddling about, dragging their tails; they seem very active and dynamic, yet they’re exhibiting behaviors that were in vogue during the Charles R. Knight era (in fact the Tyrannosaurus/Triceratops fight seems to play up the whole “eternal enemies” narrative). I couldn’t help but laugh out loud when I saw Stegosaurus menacingly flattening its plates at the offending Ceratosaurus, but I will leave a fuller discussion of stegosaurs and their armor for another day.

Knight rex triceratops
Charles R. Knight’s famous painting of a “duel” between Tyrannosaurus and Triceratops. It is one of the most well-known (if not the most well-known) images in all of paleo-imagery.








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