• The fibrolamellar smoking gun.


    Three different types of bone growth scene in vertebrates. A. Low vascular, lamellar bone. B, highly vascular, woven bone. C. Fibrolamellar bone. Arrows indicate Lines of Arrested Growth (LAGs). Image from http://ltc.smm.org/histology/
    Three different types of bone growth seen in vertebrates. A. Low vascular, lamellar bone. B, highly vascular, woven bone. C. Fibrolamellar bone. Arrows indicate Lines of Arrested Growth (LAGs). Image from http://ltc.smm.org/histology/


    For over twenty years now it has been assumed that there is a black and white divide between bone histology and thermophysiology. Automatic endothermic “warm blooded” animals tend to show a haphazard composition of bone deposition, in which bone is laid down around surrounding blood vessels very quickly, with interspersals of more organized bone deposition (for strength). The term, coined by histologist Armand de Ricqles (1980), is fibrolamellar bone.

    In contrast, bradymetabolic “cold-blooded” animals tend to show a regular deposition of layered, or lamellar zonal bone. This bone is not as well vascularized as fibrolamellar bone, and is often deposited at a much slower rate.

    Back in 1980, this evidence was used along with a chain of other circumstantial evidence to show that dinosaurs were actually “warm-blooded” animals (Bakker, 1980). This challenge did not go unanswered, and even back then there were people questioning the evidence being proposed in favour of dinosaurian automatic endothermy. As far back as 1982, there were authours claiming to have histological evidence of fibrolamellar, “warm-blooded” bone growth in crocodylians (Ferguson et al, 1982). This evidence has often been scoffed at as being questionable at best (Horner & Padian, 2004). Skeptics have pointed out that the fibrolamellar crocodylians mentioned have all been captives. Being kept in a stable environment with easy access to food has resulted in these skewed results. Wild individuals would doubtfully show these traits, as access to scenarios like those provided in captivity, are unlikely.

    For awhile this seemed to keep the argument of fibrolamellar bone, strictly in the pro-automatic endotherm camp. Well, not anymore.

    Tumarkin-Deratzian, A.R. 2007. Fibrolamellar bone in adult Alligator mississippiensis. Journal of Herpetology. Vol. 41. No.2:341-345.

    This paper reports the observation of long bone histology in alligators from Lake Griffin in Lake County, Florida. The findings are most interesting. Seven specimens were studied. Of these, three had extensive fibrolamellar growth in their long bones. In fact, one could put a fibrolamellar individual next to a lamellar zone individual and it would look like one was comparing a “classic mammal” to a “classic reptile.” The difference is incredibly dramatic; even moreso than comparing frame A with frame C in the above picture.
    That’s not the best part though. You see, these lake Griffin alligators were not only wild animals, but they were stressed animals too. Currently the Lake Griffin alligator population is suffering from an intense die off. The reasons behind the high mortality at Lake Griffin remain uncertain, but there seems to be a link to thiamine deficiency in the animals dying.

    This means that, not only are we seeing different bone deposition patterns in animals from the same population, but we are also seeing them from animals that were living under stressed conditions. This throws the whole “crocodylians can only show automatic endothermic growth rates under perfect conditions” argument right out the window.

    So what does fibrolamellar deposition really show? Currently it remains unknown. It might still indicate faster growth. What it doesn’t indicate, though, is the thermophysiological preference of the animal in question.

    Id est: it doesn’t seperate the “warm-bloods” from the “cold-bloods.”

    More to come. Stay tuned.


    Bakker, R. 1980. “The Need for Endothermic Archosaurs.” In: Thomas, R. D. K., and Olson, F. C. (eds.). A Cold Look at the Warm-Blooded Dinosaurs. Westview Press, Boulder.
    de Ricqles, A. J. 1980. “Tissue structures of dinosaur bone: Functional significance and possible relation to dinosaur physiology.” In: Thomas, R. D. K., and Olson, F. C. (eds.). A Cold Look at the Warm-Blooded Dinosaurs. Westview Press, Boulder. Pp. 103-139.
    Ferguson, M.W.J., Honig, L.S., Bingas Jr, P., Slavkin, H.C. 1982. In vivo and in vitro development of first branchial arch derivatives in Alligator mississippiensis. Progress in Clinical nad Biological Research. Vol. 101: 275-286.
    Padian, K. and Horner, J.R. 2004. “Dinosaur Physiology.” In: Weishampel, D.B., Dodson, P. and Osmolska, H. (eds.), The Dinosauria 2nd edition. Univ. California Press., Berkeley. pp. 660-671.

  • When dinos were nixed, mammals stayed fixed.

    According to news from CNN.com, (though technically, AP), mammals weren’t itching to take over the newly vacated niches left behind by the dinosaurs 65 mya.

    A new phylogenetic study of mammals, reported that there was no burst of activity following the demise of the dinosaurs. There was some flurry of speciation in animals that left no descendants, but all extant mammals remained pretty low key until around 55-35 mya.

    As is typical for these studies, the results are somewhat controversial. Some folks are questioning the dating methods used, while others are both shocked and impressed with the results.

    Though the AP sticks in the hyperbolic: “…challenges a long-standing theory.” statement, I doubt we’ll be seeing textbooks getting rewritten anytime soon.


  • Latest Paleo News

    Apparently these past couple of days have been a bit of a boon to paleontology. 3 new finds have just been announced.

    The most recent find, is that of a new species of gliding reptile from the early Cretaceous period (125 mya).

    See: New Scientist for a full description.

    The neat thing about this critter is that it is the oldest gliding lizard to date. Back in the Permian and Triassic periods, there were various gliding critters like Sharovipteryx, Coelurosauravus, and Kuehneosaurus. None of these reptiles were lizards, though.

    This new guy, Xianglong zhaoi, is the first true member of squamata that glided. The New Scientist illustration makes the critter look nearly exactly like a modern day Draco. I haven’t read the paper yet, so I’m not sure how accurate it is. Finally, another neat thing about this little guy (only 15 cm long) is that it was preserved so well that one can actually make out the wing membrane itself. Very cool stuff.

    The second bit of news is among the crocodyliformes. A new species of Metriorhynchid suchian has been unearthed in Eastern Oregon. Metriorhynchids were a completely marine group of crocodyliformes. They are easily diagnosed by their thin snouts with needle like teeth, their lack of any real scalation (in specimens that retain skin impressions) and the presence of a bifurcated, or forked tail. Imagine something like the horrible love child of a crocodile and a shark.

    Full story here

    According to the report, this new guy, who has yet to be named, lived around the middle to late Jurassic (180-150 mya). According to the report, this species retained short stubby limbs (all other Metriorhynchids evolved paddles), which suggests that it might have still made forays onto land. It was probably a coastal dweller. It must have been pretty clumsy on land, though, given its large forked tail.

    The last bit of news is in the realm of dinosaurs. Paleontologists have recently announced the discovery of an ornithischian dinosaur that was a burrower. The new dino, named: Oryctodromeus cubicularis, was found inside an ancient burrow. It also showed a couple of unique features that suggest this animal did the burrowing itself.

    One can read more on the story here.

    The paper will appear in the next issue of: Proceedings of the Royal Society B.

    Once I get ahold of these papers, I may make an update.

    Stay tuned.


  • American crocodile bounces back.

    A little over 30 years from when it was originally put on the endangered species list, the American crocodile (Crocodylus acutus), has been officially moved from “endangered” to “threatened.”

    American crocodile pick from: stockpix.com

    Crocodylus acutus

    Though the animal remains endangered in South America, in the states things seem rosier.
    In Florida the animals have gone from a scant 300 wild animals, to 2,000. Though this pales in comparison to the amazing comback that the American alligator (Alligator mississippiensis) made (over 1 million individuals live in the Southern U.S.), it is still an impressive bounceback.

    Kudos to the American croc and the conservationists who worked tirelessly to bring it back from the brink.

  • Colossal squid caught

    Once again, I’m coming late to the party on this one. It seems that fisherman in Antarctica’s Ross Sea caught the largest specimen of Colossal squid (Mesonychoteuthis hamiltoni) to date.Most folks are aware of Architeuthis dux, the giant squid.Few folks are aware of the fact that while A.dux is the longest, it’s actually M.hamiltoni that is the largest. Judging from sucker marks found on sperm whales, as well as actual remnants found in sperm whale stomachs, these guys appear to be much nastier than your garden variety giant squid.

    It’s too bad that this one was found dead already. Hopefully we’ll be able to nab some footage of these living giants, one day. Till then, we’ll have to make due with dredging up remnants of these awesome beasts.


  • Supersize crocs on PBS

    Last week the long running PBS series, Nature, showed an episode entitled: “Supersize Crocs”. The premise was to follow croc conservationist, Rom Whitaker as he attempted to see if any 20+ foot crocodiles survive today.

    Unfortunately, much like the Discovery Channel’s “In Search of the Giant Squid” documentary, the results garnered from this doc were inconclusive at best. By the end of the show, the largest croc actually found, was 18ft long. Compared to the late, great Steve Irwin’s attempts at finding giant crocs, it would appear that Whitaker was short by 1 foot. There was some allusion to a 20 foot beast that was seen briefly before it ran into the water. Unfortunately Whitaker could only give a guestimate of its size based of its slide print (which was not all that clear).

    Overall, the documentary made for a nice hour long diversion. There was a lot of crocodile measuring, and some unecessary CGI used to explain crocodylian anatomy. It also featured Croc biologist, Adam Britton, though only for about 10 seconds.

    There were, however, some problems with the program that bugged me.

    First, was the purported maximum size. Whitaker wanted to find a 20 ft croc. During the program he ran into a person who said that he had seen a 22ft individual. He said that this was 2ft longer than the longest individual ever recorded. The problem with this is that there have been reports of saltwater crocodiles (Crocodylus porosus) reaching sizes of 23 ft. While not all these reports may be valid, there are enough credible ones to suggest that they once could reach this size (Ross, and Magnusson, 1989).

    My second qualm comes from Whitaker’s statement that crocodiles grow slowly. In the documentary, Whitaker states that the largest crocodiles (the 20+ footers) would have taken 80 years to reach that size. That is a completely unrealistic statement. Most crocodylians studied to date, tend to take between 10-15 years to reach sexual maturity. At this point they are often very close to their maximum size. From this point on, growth slows substantially (though never completely stops). Large crocodiles might live to 80 years old (some may be centennial), but they don’t take 80 years to get there.
    My final problem with the program was that it continues to promote the myth that crocodylians have remained unchanged for over 200 million years. Crocodylians (i.e. Eusuchia) weren’t even around 200 million years ago. In fact, true crocodiles are a fairly recent group, having evolved around 80 million years ago (something that the Nature website gets correct, but the actual documentary does not). They are but one branch of a highly successful group of animals called crocodyliformes; which in turn are a branch of the highly successful crocodylomorphs. Finally, all are members of the Dinosaurian sister group: Crurotarsi, or Pseudosuchia (for those who would like to continue the croc naming trend).

    The only reason why crocodiles always get lumped into the “living fossil” category, is because the bodyplan that they do have, happens to have been a popular bodyplan for the past 200 + million years. Crocodylians are just the latest group to use it. Before them, there were pholidosaurs, and way before all that, we had phytosaurs.

    Calling crocs living fossils, is doing a disservice to their lineage. Just among the Crocodylia, we had such out there animals as the land dwelling, panzercroc Pristichampsus, and the weird Australian mekosuchines (e.g. Quinkana, Mekosuchus, Trilophosuchus, to name a few).

    Not to mention strange behemoths such as the “duck billed” Purussaurus.

    Regardless, the point is that crocs are way more diverse than they are ever given credit for.

    Overall, I’d say the best part of the entire documentary would be the scenes of freshwater crocs (C.johnstoni) galloping into the water.

    Oh, and the only reason I’m bringing this up now is because I just saw it last night.


    Refs:Ross, C.A. and Magnusson, W.E. 1989. “Living Crocodilians” in Crocodiles and Alligators. Ross, C.A. ed. Facts on File pg: 68

  • Virgin Dragons and Fossil Sharks

    This is more of a catch-up post than anything else. A few months back, it was announced that Flora, a Komodo dragon had laid fertile eggs even though she had never been with a male dragon. Now, just last week, it was announced that the eggs hatched.

    The overall story is interesting, for it shows that parthenogenesis is more common in reptiles than previously thought (the original suggestion for this came from a timber rattlesnake [Crotalus horridus] that also gave birth to young without the aid of a male). Surprisingly the story doesn’t mention the sex of the babies. Reptiles that have genetic sex determination, rely on ZW and ZZ chromosomes. Unlike mammals, though, the heterogametic sex is female (i.e. they have the ZW chromosomes). This means that in a parthenogenic clutch of eggs, the choice of chromosomes is either ZZ (male), or WW (infertile), but never ZW. As such, all parthenogenic hatchling reptiles and birds, are male (there are exceptions for certain all parthenogenic species, but they create all females by doubling [tripling] their chromosomes). This has implications for colonization. A parthenogenic female can give birth to male offspring, which can then mate back to the mother (nasty, I know), and produce a more even sex ratio and a more stable blood line. Perhaps it’s because males are the heterogametic sex in mammals, that parthenogenesis is not found in this group. A female that can only give birth to other females, is far less likely to make a lasting line in new environments.

    The second bit of interesting news, comes from Japan, where scientists report the discovery of a rare ancient shark. The frilled shark (Chlamydoselachus anguineus) is a rare site, as it usually lives hundreds of meters below the surface. The video that Reuters (and other news outlets) has, is stunning to watch. The shark almost looks like an animatronic piece of Hollywood fiction. It was unfortunate that this female didn’t survive. Hopefully we will be able to capture footage of healthier individuals in the future.

    That’s it for now.


  • New Site Design

    Well the Reptipage has been up for almost 9 years now. Sadly, about 5 of those years were spent in stasis. Due to lack of time on my part, as well as lack of resources (both academically and developer wise), my site quickly became stagnantt. I’ve finally decided to change that, and the first step is to drag my site kicking and screaming, into the land of Web 2.0.

    Hence, the blog.

    Personally, I hate that term. Before weblogs were known as blogs, they were originally just called: “What’s New.” It was a simple phrase that was illustrative of what one would expect (i.e. new developments on the site). This blog is going to follow more along these lines.

    That said, I also intend to use this space to talk about the latest news stories involving natural history. Especially the natural history of reptiles and their ilk. For despite 9 years of service online, the web is still remarkably deficient in reptile information (with the exception of the ever growing field of herpetoculture).

    Since blogs allow for user feedback, I welcome responses. Over the years I’ve also received various e-mail questions, but have rarely had the time to answer them. I hope that by offering the option for instant feedback here, I’ll be able to answer more questions effectively. If I don’t, there’s a good chance that someone else who is reading the comments, can lend their 2 cents in.

    Expect a fair amount of changes over the next month, or two. Hopefully I’ll be able to finally execute some of the grander ideas that I’ve had for the site. All the previous pages are still available. Just use the links on the side bar to get to where you want to go.
    Stay tuned.