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  • New Siberian ornithischian and the (over) feathering of dinosaurs…again.

    Artist's impression of the fleshed out Kulinda specimen. Image by Andrey Atuchin
    Artist’s impression of the fleshed out Kulinda specimen. Image by Andrey Atuchin

    Well, as is often the case, this post is a bit late to the party, despite starting early. Unless you have been living under a rock (or don’t care that much about dinosaurs), you have probably heard about the discovery of a small ornithischian from Siberia, Russia that apparently sports feathers as well as scales on its body. It’s a crazy half-and-half animal that has given many the green light for making all dinosaurs feathery.

    As is often the case with these studies I am writing to urge caution against taking things too far, if just so there is some voice of dissent out there in an internet fully of trigger-happy feather reconstructions.

    Let’s start from the beginning.

    Continue reading  Post ID 1079


  • Tall spines and sailed backs: A survey of sailbacks across time

    One of the quintessential depictions of prehistoric times is that of an ancient, often volcano ridden, landscape full of animals bearing large showy sails of skin stretched over their backs. Sailbacked animals are rather rare in our modern day and age, but back in the Mesozoic and Paleozoic there were sails a plenty.

    By far the most popular sailbacked taxa of all time would be the pelycosaurs in the genus Dimetrodon. These were some of the largest predators of the Permian (up to 4.6 meters [15 feet] long in the largest species). Dimetrodon lived alongside other sailbacked pelycosaurs including the genus Edaphosaurus. These were large herbivores (~3.5 m [11.5 ft] in length) that evolved their sails independently from Dimetrodon. The Permian saw many species of sphenacodontids and edaphosaurids, many of which sported these showy sails (Fig. 1. [1–8]).

    SailbackRoster
    Fig. 1. A brief survey of the sailbacks of prehistory. Permian sailbacks, the sphenacodontids: Dimetrodon(1), Sphenacodon(2), Secodontosaurus(3), and Ctenospondylus(4). The edaphosaurids: Edaphosaurus(5), Ianthasaurus (6), Echinerpeton(7), Lupeosaurus(8). The temnospondyl: Platyhystrix(9). Triassic sailbacks, the rauisuchians: Arizonasaurus(10), Ctenosauriscus(11), Lotosaurus(12), and Xilousuchus(13). Cretaceous sailbacks, the theropods: Spinosaurus(14), Suchomimus (15), Acrocanthosaurus (16), and Concavenator (17). The ornithopod: Ouranosaurus (18), and the sauropod: Amargasaurus (19). Image credits: Dmitry Bogdanov (1–2, 8, 14–15), Arthur Weaseley (5, 19), Smokeybjb (7), Nobu Tamura (3–4, 6, 8–9, 10–12), Sterling Nesbitt (13), Laurel D. Austin (16), Steven O’Connor (17), Sergio Pérez (18).

    However sails were hardly a pelycosaur novelty. The contemporaneous temnospondyl Platyhystrix rugosus (Fig. 1 [9]) also adorned a showy sail.

    Fast forward 47 million years into the Triassic and we find the rauisuchians Arizonasaurus babbitti, Lotosaurus adentus, Xilousuchus sapingensis, and Ctenosauriscus koeneniall bearing showing sails on their backs (Fig. 1 [10–13]). Much like in the Permian, many of these taxa were contemporaneous and, while related, many likely evolved their sails separately from one another.

    There are currently no fossils of sailbacked tetrapods in the Jurassic (as far as I know. Feel free to chime in in the comments if you know of some examples). However the Early Cretaceous gave  us a preponderance of sailbacked dinosaurs (Fig. 1 [14–19]) including the cinematically famous theropod Spinosaurus aegyptiacus, the contemporaneous hadrosaur Ouranosaurus nigeriensis, the gharial-mimic Suchomimus tenerensis, the potentially dual sailed sauropod Amargasaurus cazaui, as well as the allosauroids Acrocanthosaurus atokensis, and Concavenator corcovatus. Lastly, the discovery announced last year (and just now coming to light in the news) of better remains for the giant ornithomimid Deinocheirus mirificus have revealed that it too may have sported a small sail along its back.

    Once again we find a group of related, largely contemporaneous, animals, most of which probably evolved their sails separately.

    Such a huge collection of sailbacked animals all living around the same time (and sometimes the same place) has begged for some type of functional explanation. The usual go-to for large, showy surfaces like these or the plates of Stegosaurus has been thermoregulation. The thinking being that blood pumped through a large surface area like this, when exposed to the sun, has the ability to warm up faster than other areas of the body. Conversely when the sail is placed crosswise to a wind stream, or parallel to the orientation of the sun, heat will radiate out into the environment faster than other areas of the body. That most sailbacked dinosaurs were “localized” to equatorial areas, coupled with the large sizes of all the taxa (1-10 tonnes depending in species) has favoured a cooling mechanism function for dinosaur sails. Whereas a heating function has been presumed to be the primary function for sails in Dimetrodon and Edaphosaurus. No real function has been ascribed to the sails in rauisuchians or Platyhystrix, though this is probably due to a lack of knowledge/interest in these groups.

    Alternate functions proposed for these sails have included a self-righting mechanism for swimming, sexual signaling and other presumed display functions. In certain cases, namely Spinosaurus aegyptiacus and Ouranosaurus nigeriensis, it has even been argued that the enlarged spines did not support a sail, but rather were supports for a large, fatty hump akin to that of camels or bison (Bailey 1996, 1997).

    Given the wealth of hypotheses for potential sail functions it would be beneficial to first understand what extant sailbacked taxa use their sails for. Unfortunately—though unsurprisingly—there are few if any scientific studies on sail use in extant sailbacked animals. This has lead to the apparent assumption that there are no extant vertebrates with sailbacks.

    There are, in fact, quite a few sailbacked animals alive today. These include various fish, amphibians and even reptile species. Learning what these taxa use their sails for may offer us a glimpse at what extinct animals were doing with their sails.
    Continue reading  Post ID 1079


  • It’s over 9,000!

    Last year was a busy year for me. As such the site had to go into dormancy yet again. This year doesn’t look to be any less hectic, but I couldn’t bear to have the site continue to stagnate. So in an attempt to jump-start things again I am going to try and push out some smaller updates.

    Which brings us to our topic.

    The Reptile-Database recently released the current known/generally accepted species count for reptiles. It is now at a whopping 9,952 species! For comparison, when I was growing up the standard species count for reptiles hovered around 6500–6700 species. In fact one can still probably find this widely cited figure in books today. Even when I started the Reptipage some 16 years ago, the total species count was approximately 7,500 species. So in the span of those 16 years, our knowledge of extant reptile diversity has grown by 33%. That’s pretty impressive. Especially when compared to other amniotes. For instance birds are routinely cited as having 10,000 species. The most recent species count for Aves is: 10,530 (IOC World Bird List), an increase of just 5.3%. Mammals were cited as having 5000 species when I was growing up. The most recent (2008) count I could find shows that this class now contains 5,488 species (IUCN Red List); an increase of only 9.8%.

    Part of the reason for the larger spike in reptile species counts vs. mammals and birds is due to a new interest in reptiles themselves. Much of the history of Reptilia is one of revulsion, lumping, and overall wastebinning. However, now with the rise of herpetoculture and the acknowlegement that reptiles represent more than just a “stepping-stone” towards mammals and birds, herpetology has seen a bit of a renaissance in taxonomy. Another reason for this spike in species counts for reptiles can be attributed to the use of molecular techniques to ascertain differences in populations, along with better morphological data (such as those used to help determine that Crocodylus suchus was a real species and not just a variant of the C. niloticus) as well as better ecological data. This spike in species count has come about largely through the elevation of subspecies rather than the discovery of new species (though that is still happening). Herpetology has had a long history of lumping taxa that seem similar enough. This reluctance to split populations into distinct species rather than populations variations had artificially limited the actual species counts. Along with the elevation of subspecies to full species, there has also been a trend to elevate many subgenera to full genus status. This move is somewhat more controversial as the question always pops up of what the ever moving criteria for a genus are. Of course the criteria for species are hardly set in stone either. Ultimately taxonomy is a largely arbitrary affair of biological bookkeeping. Despite this, the need to have these criteria is paramount. The human brain doesn’t work well without categories, even if they are largely self-imposed ones. The appeal of splitting up Reptilia like this is that it reflects a changing attitude about reptiles in general. Though it has been long known that reptiles outnumber mammals, there always seems to be an undercurrent of “but they’re all just the same lizard.” A view that reptiles may be speciose, but are still limited in their body shapes compared to mammals and birds, still pervades today. Hence one reason why there are 29 orders of mammals, some 23 orders of birds, but only 4 orders of reptiles. A move to upgrade subspecies to species and subgenera to genera adds greatly to dispelling the myth that reptiles are the forgettable “intermediate forms” on the tree of life.

    Example of the different “genericometers” of taxonomists. Top left–right: Different members of the Anolis genus: A. proboscis and A. sagrei. Bottom left–right: Different genera of wild cats: Leopardus pardalis and Leptailurus serval. Anolis photos from: Lucas Bustamante and lanare (wikipedia). Serval photo from Giuseppe Mazza. Ocelot photos is unattributed but widely found on the internet

    Regardless of these higher order relationships it looks like Reptilia will officially comprise over 10,000 species by the end of the year [Note: See the comments].

    That is pretty awesome.

    ~Jura


  • “Feathers” on the big, “feathers” on the small, but “feathers” for dinosaurs one and all?

     

    Yutyrannus artwork by Brian Choo. Sciurumimus artwork by Arkady Rose

    This year has seen the discovery of two big deal dinosaur specimens. At least they are a big deal in regards to dinosaur integument and, possibly, metabolism.

    First off from a few months ago we had the announcement the theropod Yutyrannus hauli, the “beautiful feathered tyrant.”

    Xu, X., Kebai, W., Ke, Z., Qingyu, M., Lida, X., Sullivan, C., Dongyu, H., Shuqing, C., Shuo, W. 2012. A Gigantic Feathered Dinosaur from the Lower Cretaceous of China. Nature. Vol.484:92-95

    This was not just a single fossil, but a collection of three fossils (one might be tempted to call it a family group, but that would only be speculation). As with all other dinosaur fossils that have been found to have filamentous integument, these guys come from Liaoning, China. They are suspected to have come from the Jehol Group in the Yixian formation. I say suspected because the complete three specimen set was a purchase from a fossil dealer, an all too common occurrence for Chinese fossils. As such the provenance information is unknown. A lot of Chinese fossil dealers don’t like to give away the location of their find due to the potential loss of other profitable specimens. This current trend in China is a good example of what happens when capitalism comes into play with fossil collecting (something that the U.S. has been mostly, but not entirely, able to avoid). So it is currently uncertain whether these fossils are from the Yixian. However given that all the others guys are too it is probably a good bet. Given the sketchy nature in which many Yixian fossils are collected, coupled with the possibly large consequences of the find, one should naturally be skeptical of the fossil. Had it been one individual on multiple slabs I would question its validity as a real thing. However since Y.huali is known from three individuals, and the filaments seem to follow a consistent pattern around the body (compare that to the helter-skelter nature of Tianyulong‘s preservation), forgery seems unlikely. These guys are probably the real deal. This has some potentially far reaching consequences to interpretations of Late Cretaceous coelurosaurs and the Jehol Biota itself (more on this in a bit).

    The second announcement came just a few weeks ago. This was the discovery of a potentially new, miniscule theropod from Bavaria Germany.

    Rauhut, O.W.M., Foth, C., Tischlinger, H., Norell, M.A. 2012. Exceptionally Preserved Juvenile Megalosauroid Theropod Dinosaur with Filamentous Integument from the Late Jurassic of Germany. PNAS Early Edition:1203238109v1-201203238.

    The specimen is exceptionally well preserved. So well preserved in fact that it actually looks like a plastic toy. While this degree of preservation warrants importance all its own, the main interest behind this new guy—dubbed: Sciurumimus albersdoerferi (Albersdörfer’s squirrel mimic)—is the apparent presence of filamentous integument on the body coupled with its apparent placement among much more basal theropods. This discovery has far reaching consequences for theropod integument interpretations. Note: As with Y.hauli, Sciurumimus albersdoerferi was also purchased from a private collector. I don’t suspect forgery here either as this was in Germany, where fossil dealing is neither a big problem nor a lucrative business. The exceptional detail on the specimen would also require a substantial amount of theropod knowledge to pull off. Anyone having that amount of knowledge is more likely to be a real paleontologist than a get rich quick forger.

    Continue reading  Post ID 1079


  • Back up and running

    This pretty much says it all

    As folks earlier this week might have noticed the site was blacklisted by Google. It turned out some hacker’s bot had infiltrated my WordPress account and inserted a bunch of nasty redirects to malware sites.

    Getting hacked at any time is shitty, but finding the free time to deal with this was problematic. I have spent many late nights (leading to early mornings) this past week trying to fix things. The hardest part wound up being the frigging permalinks. On the bright side the site is back in working order. This was a sobering reminder for me to take better care of my site, lest some malware bot look at it as abandoned property. Real life work has kept me distracted from the site, reducing its output considerably. I intend to fix this soon as I have a few posts simmering and almost ready for prime time. I intend to keep the Reptipage up and running for as long as possible. That includes keeping it updated with new content.

    Sorry for the delay folks. We can now return to our regularly scheduled blogging.

    ~Jura


  • Turns out that plesiosaurs gave birth to live young. It’s about damned time.

    _Polycotylus latippinus_ mother giving birth to young in a very cetacean-like fashion. Illustration by: S. Abramowicz

    Just announced today in Science, researchers at the Marshall University and the Los Angeles County Museum described the presence of fossil young inside the body of the plesiosaur: Polycotylus latippinus. The results of their find seem to confirm what has been suspected for quite some time now, that plesiosaurs were viviparous animals.

    O’Keefe, F.R., Chiappe, L.M. 2011. Viviparity and K-Selected Life History in a Mesozoic Marine Plesiosaur (Reptilia, Sauropterygia). Science. Vol.333(6044):870-873

    The evidence had been mounting for some time now. While plesiosaurs came in numerous shapes and sizes, most of those sizes were in the large to giant range measuring in at multiple tonnes (e.g. Liopleurodon and Kronosaurus). That is a lot of weight to attempt to drag up on a beach for egg laying. Further, though the rib cage is well braced ventrally, the limb girdles are not braced against the vertebral column. This would make it very hard for a large landlubbing plesiosaur to make any kind of headway as the limbs would have no leverage against the body for dragging itself on land.

    Lastly, and perhaps most importantly, we have known of at least one plesiosaur fossil that had embryos in it. This has been known for at least five years now (I learned of it four years ago, and it has been hinted at before [Smith 2008]). Sadly this specimen still remains unpublished. This new paper by O’Keefe and Chiappe goes on to mention the relatively large size of the young, estimated at 1.5 meters when born. This was much larger than the young of other large extinct and extant marine reptiles. The authors (cautiously) suggest that this might hint at a different life history for plesiosaurs vs. other marine reptiles. They posit that plesiosaurs might have nurtured a small amount of relatively large young, which in turn might have meant that they were more social than previously thought.

    Naturally this has resulted in the inevitable comparison to whales. While a “pod of plesiosaurs” does sound interesting, we have far too little evidence to say if such a thing ever happened (and the authors state this too). What we do know is that young plesiosaurs have been found in shallow marine settings. These have been posited to have been “nurseries” where young could stay out of sight from predators while reaching adult size (Martin et al. 2007). Whether, or not adults stayed around, or if they joined a “pod” later (if at all) is all unknown. Still, it is nice to see some validation to what seemed almost necessary for so long.

    Admittedly not everyone is convinced (a good thing to see in science). Dr. Ken Carpenter of the Utah State Museum offered Science magazine a dissenting view, suggesting that the position of the young could still indicate that these were juveniles that had been eaten. The O’Keefe and Chiappe considered this in the paper and pointed out that the skeletons lacked any signs of acid etching, as well as showed numerous skeletal bones that did not appear fully ossified. Further analysis could shed more light on this. Publishing on that other plesiosaur could really help things out too.

    Viviparity - could these guys be next? Image from the Nature Museum in Stuttgart.

    Assuming that we are looking at viviparous plesiosaurs, that just leaves two other large marine reptile groups of the Mesozoic. Turtles and Crocodylomorphs. In both cases we have extant animals that are obligate oviparous animals, but there might still be reason to think that live birth might have evolved in these groups too. Again, much like with the plesiosaurs, the groups in question (protostegid sea turtles and the podocnemid Stupdendemys, as well as metriorhynchid crocodylomorphs) have members that grew extremely large. While Protostega gigas may have been able to haul itself out on land as extant leatherbacks (Dermochelys coriacea) do, it seems harder to justify that in the much larger Archelon ischyros; an animal that has been estimated to tip the scales at 2 tonnes. Given the amount of effort it takes a large female leatherback (~1 tonne) to haul herself up and down a beach (not to mention the damage it causes to the animals in the short term), it would be all the more amazing if A.ischyros was able to pull off such a feat. The same would go for the metriorhynchids, who had adapted completely to a marine lifestyle (i.e. they had flippers and a tailfin). If a 5 meter Gavialis gangeticus can barely move around on land, I’d hate to see what a 5 meter Dakosaurus would look like. To date we have no evidence one way, or the other for these last two groups. There is a bit more resistance to the idea of viviparity in these groups as no extant members exhibit viviparity. This has lead some to wonder if the calcified eggs of archosaurs (and many chelonians) might prove a phylogenetic constraint on live bearing (the young absorb calcium from the shell, which could mess up calcium absorption in a taxon evolving along the lines of viviparity). The chelonian shell — in turn — may also have been constraining on the size of young that can be held in the body cavity. Still, to date, there are no nests, eggs, or embryos for any of these taxa, thus leaving the matter open for debate. It is interesting that neither protostegids, nor metriorhynchids got to the huge sizes of mosasaurs, ichthyosaurs and plesiosaurs, but that could have been for any number of reasons including the simple lack of finding the larger taxa yet. Until then the physics vs. phylogeny argument remains unresolved.

    Anyway, compelling evidence for live bearing in at least some plesiosaurs. Woohoo!

    ~Jura

    References

    Martin, J., Sawyer, F., Reguero, M. Case, J.A. 2007. Occurrence of a Young Elasmosaurid Plesiosaur Skeleton from the Late Cretaceous (Maastrichtian) of Antarctica. 10th Int.Symp.Antarctic Earth Sciences.
    O’Keefe, F.R., Chiappe, L.M. 2011. Viviparity and K-Selected Life History in a Mesozoic Marine Plesiosaur (Reptilia, Sauropterygia). Science. Vol.333(6044):870-873
    Smith, A.S. 2008. Fossils Explained 54: Plesiosaurs. Geol.Today. Vol.24(2):71-75

     


  • The 3D alligator

    Model organisms are a staple of biology. They are taxa that are used to answer larger questions about that group as a whole, or some general biological problem. Model organisms are chosen for their ease of handling, cheap acquisition, generally “generic” structures, or all of the above. Every major class has a model organism to represent it. Just among vertebrates we have:

     

    A stillborn hatchling rests inside the left nostril of a large 3.7m (12ft) adult which is some 5000 times larger!
    A stillborn hatchling rests inside the left nostril of a large 3.7m (12ft) adult which is some 5000 times larger!

    Mammals with mice (Mus musculus), dogs (Canis familiaris [or Canis lupus familiaris if you lean that way]), cats (Felis catus [or Felis sylvestris catus for the same reason as dogs]), guinea pigs (Cavia porcellus) and rhesus monkeys (Macaca mulatta).

    Birds with chickens (Gallus gallus), pigeons (Columba livia), and zebrafinch (Taeniopygia guttata).

    Ray finned fish with zebrafish (Danio rerio), swordtails (Xiphophorous) and cichlids (Cichlidae).

    Amphibians with the African clawed frog (Xenopus laevis), and axolotol (Ambystoma mexicanum).

    Reptiles with anoles (Anolis), fence lizards (Sceloporous), painted turtles (Chrysemys picta) and finally, the American Alligator (Alligator mississippiensis).

    Alligators are relatively new to the model organism realm, but they have proven to be extremely informative. They seem to the be most even tempered of extant crocodylians, making them “more safe” for researchers to work with. Hatchlings start off as miniscule 68 gram (0.15 lbs) animals that later can grow to 363 kg (800 lbs) adults, passing through an enormous size range throughout ontogeny. This growth rate is very food dependent, making it possible to raise alligators almost as bonsai trees. Also, with their unique position on the organismal family tree, alligators are one of the closest living relatives to dinosaurs. Along with birds, they have the potential to help constrain our assumptions about dinosaurs; thus making them very popular subjects for paleontological research as well.

    Today, alligators get to make one more stamp on human knowledge with the release of the 3D alligator project from the Holliday and Witmer labs.

    Researchers from both labs went through the painstaking process of digitizing the skulls of an adult and a hatchling American alligator, and then digitally separated each bone. The result is a 3D model that can have each bone turned on and off at will. The neat thing is that both labs have made these data freely available for anyone to look at, and download as 3D pdfs, wirefusion models, and multiple movies.

    So if one every wanted to know just how many bones make up a crocodylian skull, or how each bone aligns to each other, I highly recommend downloading the 3D pdfs of the adult and hatchling. Not only will one learn all the different bones that compose the skull, but by comparing hatchling to adult, one can see just how radically these bones change throughout ontogeny.

    It’s neat, free, informative and reptilian. What more can one ask for. 🙂

    ~Jura


  • Metabolism part I: The importance of being specific

    From archaea to blue whales. Metabolism is a hallmark of all living things

    Metabolism, and metabolic rate tend to feature pretty highly in literature related to dinosaurs and other reptiles. For instance it is often stated that reptiles have metabolic rates around 1/10th those of similar sized mammals and birds, but what exactly does that mean? Talks of thermoregulation focus heavily on the role of metabolism, while allometric studies focus on how metabolism is affected by size. Given the prevalence of metabolic terminology in dinosaur and reptile papers/books, I thought it might be best to quickly give a review of metabolism, metabolic studies, and what all of that means for real animals.

    Metabolism is everything


    Metabolism is defined as the sum total energy expenditure of an organism. That is to say metabolism is the total energy an organism uses during its life. It is often broken up into the chemical reactions that build up resources (anabolism) and the reactions that break those resources down (catabolism). The amount of metabolism, or energy expenditure during a specific interval of time (seconds to days) is referred to as metabolic rate. From bacteria to blue whales, metabolism is the measure of all the energy that lets these critters go, and metabolic rates determine how much energy that is going to take. It can be measured in a variety of ways from respirometry to doubly labeled water and heart rate telemetry. The diversity of metabolic rate measurements is reflected in the units used to measure metabolism; which can range from watts/hour to milliliters of oxygen per minute, and even to joules per second.

    Specificity is important


    A key thing about metabolic rates is that they are plastic. They change depending on the situation presented. For instance one could measure the metabolic rate of a sleeping cat, and then compare it to measurements from that same cat while playing, or after eating a big meal. Metabolic rates ramp up when energy demand increases, and then ramp down when that energy demand decreases, or when the environment demands drastic energy cuts (e.g. starvation). Thus when measuring the metabolic rate of an animal it is important to decide exactly what kind of metabolic rate you are trying to measure.

    And boy, oh boy are there a lot of different flavours to choose from.

    One can measure: BMR, SMR, RMR, MMR, AMR, and FMR just for starters.

    Those are a lot of initialisms, and they are just the most common ones. The choice of metabolic rate that one decides to measure is also going to dictate the technique that will be employed. So what do all these things stand for, and what technique is best for what? Let’s find out.
    Continue reading  Post ID 1079


  • Nile crocodile takes on elephant

    The site has been pretty slow for the past couple of months as academic life has eaten up a lot of my free time. That should change in a few weeks (and I do have a doozy of a post I have been working on).

    For now though I leave folks with this amazing photographic account of a Nile crocodile (Crocodylus niloticus) attacking an adult mother elephant (Loxodonta africana).

    Photos by Martin Nyfeler. Be sure to click on the image for the full account of what took place (complete with more photos)

    Whether, or not the crocodile meant to try this, or if this was an accidental predation attempt remains unknown. While this might be the first time this was caught on film, it is not the only account of this. Nile crocs have been known to attempt to take down large elephants by grabbing onto their trunks. The initial attack is almost always unsuccessful, but if the croc winds up doing enough damage it can result in the elephant dying days later (as a broken trunk pretty much limits all access to food). Not sure if the crocs ever benefit from this, but the fact that they can kill large adults is enough to make them a formidable threat to any thirsty elephant.


  • T-U-R-T-L-E Power Part 3: Leatherbacks Break All the Rules.

    Leatherbacks are already viewed as unique, but you might be surprised at just how strange this species really is. Picture from: amigosdomarnaescola.com

    Continuing the series, let us now take a look at one weird turtle species in particular: Dermochelys coriacea, the leatherback sea turtle.

    While the utter weirdness of D.coriacea is ultimately the main reason for why it wound up in this series, there is an ulterior motive. Having searched the internet for general information on the species I found myself rather disappointed with the amount of utterly generic / wrong info regarding leatherbacks. Its Wikipedia entry is particularly disappointing. So here’s hoping this influx of information can help alleviate that.

    A turtle without a shell?

    Yes, it’s true, leatherback turtles have lost their shells. Shell reduction is relatively common in turtles. It seems a little funny. After going through all the trouble of evolving impregnable armour, many taxa then went out and removed large chunks of it. We see shell reduction in snapping turtles (Chelydra and Macrochelys), soft-shelled turtles, and even other sea turtles. None of them, however, reduced their shells to the point of actually removing them.

    In leatherbacks the “shell” is nothing more than a loose collection of osteoderms spread over the back and belly. There is no longer a definitive carapace, or plastron. In fact leatherbacks don’t even produce Beta-keratin (the hard component of reptile scales). Instead this has all been replaced by thick, leathery skin.

    Continue reading  Post ID 1079