Deprived Children

Clidastes has no "for kids" links, sadly. It has very little in the way of child oriented goodness associated with it actually. Considering it is Easter still here in the US there probably is not too much demand for an ancient sea monster anyhow today; most of the kids I know are already in jelly bean comas. Regardless, here is a little adaptation of the fact presentation put together by Bob Strauss for About.com:

Name:

Clidastes; pronounced klie-DASS-tease

Three species are recognized:

• C. propython Cope, 1869
• C. iguanavus Cope, 1868
• C. liodontus Merriam, 1894

Habitat:

Oceans of North America

Historical Period:

Late Cretaceous (75-65 million years ago)

Size and Weight:

At its smallest: 10 feet long and approximately 100 pounds

The largest Clidastes recovered was approximately 20 feet long and probably would have weighed close to 200 pounds

Diet:

Fish and marine reptiles

Distinguishing Characteristics:

Small, sleek body; fast swimming speed

About Clidastes:

Like many other mosasaurs, fossils of Clidastes have been found in areas of North America (such as Kansas) that were once covered by the Western Interior Sea. The first Clidastes of note was unearthed in Alabama along what would have been, at the time, the eastern edge of the WIS. It was on the smaller end of the mosasaur spectrum. Clidastes was, however, a fast and agile swimmer capable of chasing down prey items that were quite fast.

Tail Oars

The late great Dan Varner (©), a king of marine animal illustration

Clidastes, as the smallest mosasaur, is unique in that way at least. Its small size allowed it to be a quick and agile swimmer that was capable of chasing down some quick and diverse types of prey. In this Dan Varner illustration a Clidastes is chasing down a turtle, which may or may not be a preferred food item. Considering the smaller teeth of Clidastes I would think that a turtle would not be a main dietary choice for these animals, however, this depiction could be of a young mosasaur as well. Young mosasaurs, if they were independent hunters, under a mother's supervision and encouraged to indulge their interests and learn for themselves (or they were orphaned) may have attempted to eat prey that they would not normally have attempted to delve into. Also, for the future discussions, in about ten seconds, note the caudal limbs and the thick paddle of the tail.

The tail and caudal limbs are of important note in all illustrations of Clidastes are important to pay attention to. At times the tail appears somewhat fish-like, like an Ichthyosaurus tail, and sometimes, as in all the illustrations I picked today, the oar shaped tail is dominant. There is a difference of opinion amongst experts and most seem to prefer the oar shaped tail, though, considering that there would likely be no bones in a large fish-like tail, the possibility of a strong swimmer such as Clidastes adapting to its environment by developing a large fish tail rather than an oar like tail like its bigger cousins and sisters is not very far fetched. However, the oar shaped tail could be just as powerful as a deep fish tail if it too was deep and had sufficient muscle attachment to power it. The caudal limbs I also suggest noting due to the fact that the caudal limbs are never illustrated in the exact same manner. In this illustration the limbs are rather hand like, at times they are paddle like and other times they seem to be not much larger than the pelvic fins of sharks.

©Dmitry Bogdanov

The mid-sized caudal limbs of many illustrations are fairly typically ovals attached to the body. The oar shaped tail here is nice and deep, conveying that sense of power a bit more than a shallower oar. The head, I think, is a bit more Tylosaurus like than it is Clidastes like, however, considering we do not have a "mummified" Clidastes skull to compare the skin impressions to the fleshed out drawings and illustrations of modern artists. The agility of Clidastes, somewhat rarely overall, is shown here as it is chasing down some small and fast prey items. Overall, most Clidastes images look very similar, and consensus in the art community is not a bad thing, but there is enough variation between artists and images exists that looking at these images in contrast to one another can be an all day activity.

The Smallest Mosasaur

At between 7 and 12 feet (2 and 4 meters), Clidastes is the smallest of the mosasaurs; the longest specimen discovered is approximately 20 feet (6.2 meters) long. Like last week's smaller plesiosaur Dolichorhynchops, Clidastes' smaller size, in part, led to a faster mosasaur capable of chasing down quick prey with relative ease. Clidastes had special adaptations that, with the smaller more compact size of the reptile, allowed for strong muscles to be attached to the body in key areas, such as the tail, that would have generated massive amounts of propulsion for this animal. We can look at those adaptations over the week as well as looking at exactly what a Clidastes would be chasing down and chomping into as well. Clidastes, it is important to note, is a genus comprised of 3 accepted species (the 4th Clidastes moorevillensis, remaining doubtful at the moment): C. propython Cope, 1869; C. iguanavus Cope, 1868; and C. liodontus Merriam, 1894. Clidastes propython was named after C. iguanavus but is considered the neotype. Clidastes was discovered, originally, in Alabama, but has since been recovered from many other areas that were once near-shore environments of the Western Interior Seaway including, maybe most notably, the soils of Kansas; though I could be biased seeing as how I am in Kansas these days. 

©Andrey Atuchin

Well Known Polycotylids

We have shared information about books, movies, and even stuffed animals this week. For not being a household name Dolichorhynchops is a fairly popular prehistoric marine reptile; maybe it is the name that keeps this agile swimmer out of the public eye more than anything else. One thing we have not shared is the toys that are, supposedly at least, representative of Dolichorhynchops. One would think that something like Dinosaur King would have hit on these marine reptiles as part of the game and/or the cartoon, however, it has not; I guess the creators are leaving the water to the Pokemon.

However, toys have come a long way and even the cheaper toys are now becoming more accurate (we are not talking about the dollar store bag of dinosaurs of course) representations of prehistoric life that sometimes rival and even surpass the models put out in the market by the more expensive makers (we are all looking at you Safari LTD.). This toy model, for instance, was produced by Wild Republic for Nat. Geo's line based out of the "sea monsters" movie, not to be confused with the Dolly given out at Jack in the Box to promote the movie; talk about marketing in all available niches! Wild Republic also produced the stuffed animal shared the other day. This plastic figure has since been cancelled, unfortunately, but there are still other figures, such as the one produced by Collecta, that are moderately priced, as far as prehistoric toys are concerned, at between $9 and $10 depending on where it is purchased (a "sea monster" tube from Safari LTD. that contains 9-10 mini figures costs approximately the same amount).

So Much To Do

I said before that a lot of my work at present is a lot of reading and background researching. Dolichorhynchops figures into this a lot right now. Some days, like today, I have to put away the work though as it just seems like far too much to read and look over. There is a lot of information to reconcile out there depending on the researcher. The papers I shared yesterday all mention Dolichorhynchops even if their main goal was to describe another animal or discuss the phylogenetic placement of different polycotylids. Every researcher has their own or a set of derived characters taken from another researcher and therefore, by the time someone like myself comes along, there are well over 100 characters in a few different sets which may or may not overlap or be derivations of another character in another set. I feel lost some times. When I feel that way, though, I like to just look at the bones and at illustrations, computer models in motion or stills done in any number of style, and I just like to relax my brain. Therefore, today, I say let us relax our brains with this:

There are a ton of images that I find interesting or relaxing (Walter Meyers' Cretaceous Marine Predators is another favorite for this topic but I did not ask his permission). This group of Dollies is pretty serene, so it is pretty relaxing. They seem a bit slow and awkward in this still though; I do not know if that was the intended look of the models in this scene. Also, their eyes, at this angle at least, are rather odd looking to me, as though the "fleshed out" model has no flesh over the skull really. Anyhow, I should get back to work!

Too Many Papers

Lately, because Dolichorhynchops intersects my thesis research in that there is the potential that my unidentified vertebrae could potentially belong to a "Dolly" or another short neck plesiosaur ("Trinacromerum ?" is the current catalog tag), I have read a lot more papers on Dolichorhynchops than I would be able to share here. I have read about new species (Sato 2005) and cranial anatomy (O'Keefe 2008). I have read about global interrelationships of plesiosaurs (Ketchum and Benson 2010) and I am waiting on interlibrary loans on polycotylids from Morocco (Bardet, Superbiola, and Jalil 2003 and Buchy, Metayer, and Frey 2005). The list goes on even further than that; that is only five papers and I said I have read far too many to share. Sometimes these papers have fantastic photographs and wonderful data sets and character lists (that I am in the process of trying to collect and reconcile painstakingly!). However, when I look to papers for fantastic illustrations, I always have to go back to the original sources. Sometimes these are illustrations of fantastic beasts, see Cope's drawings of the WIS, and sometimes they are beautiful pen and ink drawings of the bones themselves. In S.W. Williston's case we have two good illustrations, one by Williston himself of a fleshed out "Dolly" (1914) and another of the skull by Sidney Prentice (1903). Williston's work can be found online via JSTOR thanks to the efforts of the archival workers at Chicago's Field Museum, for one source, but rather than search through all of his papers on Dolichorhynchops I admit I borrowed the images from the Oceans of Kansas website, because it was just plain quicker!

Dolly On Film

I made note that Dolichorhynchops appears in a National Geographic special. The model and a bit of motion are portrayed above suing the model with a tiny bit of information tossed in as well. I have yet to see the special (I am admittedly behind the times when it comes to watching television and movies) but I did read the article that was written around the time that the special was released. I even have a related poster from that issue above my desk in my office; it is kind of fitting given that my project is "sea monster" related. The trailer is still on YouTube as well, which is fairly nifty I suppose. I will bet it is safe to say that, despite National Geographic being a little more reputable than, say Dangerous Ltd. (that discussion has been had and discussed enough), there is probably a little bit of showmanship going on in the special that shadows some of the scientific fact. That being said for all of the skeptical adults (or ones that worked on it and know where it went "fishy" that read this), it is geared more toward a younger and less knowledgeable audience. That, as I believe I mentioned not too long ago (Thursday), is not an excuse to teach the wrong thing to the young, but unfortunately movies will be movies until someone makes a change to the whole production process, so we live with what we have for the time being. Also, and I have to put this in today because typically the music in these is awful, here is "tribute" video with a rather interesting musical selection as background. Be wary though, not all of the pictures are actually Dolichorhynchops specimens.

Dolly Teaches Kids

Dolichorhynchops has a page dedicated to it on Kids Dig Dinos for today. There is also a good, but small, National Geographic page dedicated to Dolichorhynchops as well. Probably one of the best pages that can be shared, with minimal but useful information and not a whole lot of text, is hosted by a site called Prehistoric Wildlife. The top half, anyhow, does not have a lot of text. There are models and some small toys, and there are also movies that children may enjoy. There are also some books, including the National Geographic companion book to one of their shows (Sea Monsters: Prehistoric Creatures of the Deep). Unfortunately there are not any wonderful coloring pages to share today. One thing that children will certainly enjoy as a reminder of Dolichorhynchops is this little guy from Wild Republic:

Crushed Skulls and Wonderful Preservation

Borrowed from Oceans of Kansas

The skeleton beside us here is housed in the Sternberg Museum. This picture is a bit old considering that the skeleton is now glass rectangle in the middle of the exhibit floor meaning that it can be seen from four sides; too bad it is not near the upper walkway, then it could be seen from above as well. Regardless, it is a very interesting skeleton. The skull is somewhat crushed. The pelvic and thoracic girdles are complete and the vertebrae, those pesky little fragile bits of the back, are surprisingly well preserved; my indeterminate vertebrae I am working with are a bit crushed and smaller. The skull, though, is well preserved despite its crushed state. In all honesty, as crushed as it is, it is not so destroyed that it is falling to pieces or any such thing. I am glad they have put it in a more viewable case these days so that most every angle of the skeleton is viewable by the public.

RMDRC lists this picture as the "exhibit Dolly"

The skull, when not crushed, looks a lot more like this. Notice the triangular shape of the skull, if the mouth was closed, and the grabbing teeth. These teeth are clearly designed for grasping prey much more than breaking apart prey or cutting the prey into portions. Jaw strength was probably enough to crush some smaller prey, but, if not, I would assume that some neck thrashing, think of a dog with a toy or a crocodile's death roll, would be employed by this animal to subdue prey. The prey could then be positioned and swallowed, probably head first to fold back fins into a naturally relaxed position, at the predators leisure. In those oceans at their own leisure was most likely as fast as possible in order to be alert for other predators and other meals. Interestingly, despite what we have shared about plesiosaur being slow and relaxed swimmers, RMDRC's information concurs with the theory I mentioned as my preference yesterday; that these short necked plesiosaurs were probably fast and agile swimmers. Chasing down fish and eating them on the run must have been an interesting thing to watch and speedy hunters learning to chase prey probably played some fairly interesting games as juveniles.

©Nobu Tamura

Our first fleshed out Dolichorhynchops. Again, notice the triangular head shape (I am starting to feel like a tour guide today). Also notice that the jaw does not form a sharp point to that triangle but is blunt at the end. The head is aerodynamic, but the jaws are not made for stabbing at fish; this means that, once again, the snake-like attack popularized in the late 19th century is refuted again by even more evidence and this time not from the flexibility of the neck. Could a blunt faced animal strike like a snake in the water? It could, but think of the loss of aerodynamics in a snake strike with a blunt jaw line. It would be terrible. Anyway, the most likely mode of attack was either in chasing down prey with speed and agility or the pack mentality which would funnel prey into a large school and then darting through the middle to seize prey, again, not striking at them with the neck but using the body and grasping teeth to grab prey "on the wing" so to speak. I would almost equate Dolichorhynchops to penguins in terms of how I see them hunting and swimming in the water; they just have an extra set of flippers to propel their much larger bodies.

Dolly Stops By

Photo by Ryan Somma

Dolichorhynchops osborni is the type species of a short necked plesiosaur genus. Described in 1902 by Williston, Dolichorhynchops has had a slightly checkered past and, in the past 8 years, has had two new species assigned to the genus; D. herschelensis (Sato 2005) and D. tropicensis (McKean 2011). Many high quality skeletons of Dolichorhynchops have been recovered from the ground to this date and are on display (of course that means there are a lot of quality casts out there as well) including those at the University of Kansas, the Sternberg Museum, and the Smithsonian. At up to 15 ft (4.6m), the Sternberg skeleton (VP404) is about 10 feet long, this short necked plesiosaur, though shorter than long necked plesiosaurs, was more than likely not a much better swimmer; better for sure, but probably not that much better considering that the locomotive abilities of the animal were similar if not the same as those bigger slow moving plesiosaurs we discussed previously. Some sources disagree with this assessment, stating that these were agile and quick swimmers; I would like to put forth that theory myself but the first theory deserves equal discussion considering it has been popularized at the moment. Remember that marine reptiles had lungs and not gills, therefore, Dolichorhynchops, as well as the other marine reptiles discussed so far, lived, ate, and played near the surface of the ocean. In the slow moving theory it is likely these animals ate slower moving fish, squids, and other such animals or may have bunched animals together in tight schools then fed as groups. In the faster moving theory we would see an animal hunting down quicker moving prey, probably like a giant penguin as it danced through the water.

Books For All

Ichthyosaurus, we know, is a popular animal. It is, unfortunately, always lumped in with dinosaurs, but it does get recognition to the point that any marine reptile that looks vaguely like a fish becomes an Ichthyosaurus. That being said, an Ichthyosaur, at the family level, is represented in the Walking with Dinosaurs series which can give us some behavior modelling, if we trust the science behind the life of Ophthalmosaurus as it is presented in that episode. Ophthalmosaurus is not an Ichthyosaurus however, and as such I am not going to go into too much discussion of that behavioral model as it is significantly different; the two animals did share similar niche roles in their environments but were obviously significantly different given that they are not the same taxonomically or cladistically. Regardless, Ichthyosaurus is instantly recognizable and, as such, has spawned many toys over the years.

Photo by Dr Andre Mursch

Some toys are obviously better than others. One of those, quite obviously, simply looks like a dolphin that a company renamed for the sake of having a "dinosaur" toy.

Another area that has become a home for Ichthyosaurus related public appearance is that of the scientific storybook. Scientific storybooks always give us a little informative piece and then, as the name suggests, a story about the key animals. This is not unlike the recent Discovery trend in dinosaur shows to name the main protagonist of the story, see Dinosaur Planet for examples, and then tell a tale (a tradition in the modern era of documentary begun by WwD's "Big Al"). Scientific storybooks, however, are usually geared toward upper elementary to high school (usually a stretch in high school though) students. We can see this progression in Ichthyosaurus related scientific storybooks rather well: Start in the 4th/5th grade range with Daniel Cohen's Ichthyosaurus or with Rena Korb's Discovering Ichthyosaurus; next would be Rob Shone's Graphic Dinosaurs: Ichthyosaurus; then we have a Brooke Hartzog book called Ichthyosaurus and Little Mary Anning (a book portraying a woman scientist as diminutive and written by a woman; sexism in science is a different topic though). High school aged students would go more for books like How to Draw books and, though it is older, Ron Wilson's Ichthyosaurus type books. The point is, there is a lot of material floating around in the literature ocean of the world about Ichthyosaurus just waiting to be chased down and read by all ages.

A Short Marine History

I do love Heinrich Harder's work

The evolutionary history of Ichthyosaurus is not entirely known, but enough details have been discovered to compile a good amount of evidence of the lineage of Ichthyosaurus. Generically, because we are not too worried with exact organisms in the family line right this second, it is understood that in the late Triassic a terrestrial reptile line adapted to a semi-aquatic lifestyle over time. This semi-aquatic lifestyle slowly adapted to becoming more and more aquatic as time went by. Eventually, so well adapted to the water that terrestrial life was abandoned completely, the forebears of the Ichthyosaurus genus were fine tuning their adaptations and developing their niche in the environment. Air breathing was not abandoned, but, unlike modern marine mammals, a more fish-like propelling apparatus was formed in the Ichthyosaur tail. This probably developed from side to side tail propulsion by the ancestor reptiles. As the ability to come out on land was lost the ability to lay reptilian eggs on dry land was changed over millennia. The end result, in most marine reptiles, except the giant marine turtles, was for the amniotic egg to change and adjust over that time into an amniotic gestation within the parent which is certainly not unique in the animal kingdom either then or now; some sharks, extant reptiles, other extinct marine reptiles, and of course mammals carry fetuses internally and give birth to live young. An adaptation we have not discussed, however, is found in the ear bones of Ichthyosaurs. Many marine reptiles developed ear bones allowing for highly fluid motion which were incorporated into the skull so as to not disorient the animal underwater. However, fusion into the skull is thought to have suggested low detection rates of fish and other marine animals. Ichthyosaurus, however, had large and thick ear bones that, while suited to swimming with great agility, also allowed the Ichthyosaurs to detect prey at much longer ranges than many other marine reptiles. Their large eyes- Ophthalmosaurus, a different genus of Ichthyosaur that had probably the largest eyes of any Ichthyosaur genus- were also well suited to prey detection, and threat avoidance. Everything about Ichthyosaurs points toward, as we can see, a highly successful predator that maintained a dominance over their ecological niche for a very long time.

Plenty of Papers

Ichthyosaurus, as briefly stated before, was certainly a globally distributed and highly successful marine reptile. Evidence has been found in England, of course we remember Mary Anning, but its remains have also been found in Japan, North America (Missouri specifically), the Arctic Circle (see Jorn Hurum's talk from yesterday) and even Australia. The papers contained in the links hit a number of topics in addition to describing species from different areas of the globe. The paper from England, for instance, describes how an entire 520 mm skull was ground down into 520 cross sections of 1 mm each for study. This was done back in the early 20th century, and was somewhat common at the time; unfortunately it was the fate of quite a few fossils though it did sometimes yield interesting results. One paper that, although I am not at school this week (Spring Break and, despite plans to go in today, I hurt my back yesterday 'cause I'm old!) and therefore cannot see if it is available through the school's JSTOR, really caught my eye is A. Smith Woodward's paper on viviparity. For those out of the know, viviparity looks like this in Ichthyosaurs:

Highlighting obviously done after the fact

There are many other fossils that suggest, hint at, or display live birth in Ichthyosaurs, but I like this one best. Not only is there a young pup being born (and sadly dying) in this fossil but there is also another pup's remains in the body cavity of the Ichthyosaur. Some might say that other fossils with young in the body cavity are exhibitions of cannibalism, but a find like this is a strong suggestion against cannibalism and for live birth.

Fish-Lizard in Motion

It is always quite fun to see an amateur model of locomotion of extinct species. This Ichthyosaur is, in my opinion, pretty accurate for single direction movement along a line of travel. There is a video that supposedly refutes evolutionary theory by using Ichthyosaur fossils. I did not watch the whole thing and I am certainly not posting it here because I do not like the arguments that this sort of video tends to incite.

National Geographic has posted a talk by Jorn Hurum in which he discusses National Geographic teams' adventures on "Sea Monster Island" and the history of expedition on the island. Somewhere in there there is a little bit of discussion about Ichthyosaurs and other skeletons discovered by Americans and others that have traversed the island and excavated skeletons.

Another, last video, for the day, is a compilation of historical illustrations. In case anyone is new to reading this, I have a weakness for older illustration because, while not scientifically accurate, older illustrations are highly fanciful and they embody the whimsy of the science of paleontology. They also show what imagination would have the prehistoric world look like, that, while whimsical and fanciful, is like every fairy tale we ever heard growing up, and that, honestly, is a very interesting world to envision.

Links and Only Links

Typically I try to find all kinds of books and other videos for family days on Sundays. Today, however, I am just going to put up 2 links to read with those crazy kids in your life: Kids Dig Dinos and Enchanted Learning. Additionally, I am going to paste some coloring pictures in for you and your loved ones to color today:

Generations of Ichthyosaurs

Heinrich Harder

Growing up Ichthyosaurus was a catch all, in the same way that mosasaur and plesiosaur have been used in the past, for any fish-like reptile between the size of dolphins and orcas. The older, more fanciful Ichthyosaurus of Harder had more fish-like structuring to its tail and other body elements. All said and done, there really was not much about the body of Ichthyosaurs that Harder, and other early illustrators and paleontologists, got wrong. Ichthyosaurus was a highly stylized and fashioned reptile. It was also extremely well adapted and, over millions of years of tweaking and successive adaptations of the body plan of the animal, became, roughly, the equivalent of modern dolphins and orcas in terms of agility and predatory nature. Despite a diet that consisted, evidence supports, mainly squid, this was a fast and acrobatic highly adapted reptile that was entirely marine in habitat and behavior.

©Nobu Tamura

That body plan of speed and agility remained nearly unchanged once adapting to what we might consider its pinnacle or most well adapted form. Using evidence, and I sound a bit repetitious here, we know that the body of Ichthyosaurs, in their height of marine dominance, was that akin to a dolphin's and we have evidence, to be shown shortly, that they gave live birth in a manner reminiscent of modern marine mammals. As such, we can make some general assumptions, essentially educated guesses, pertaining to the behavioral structure of Ichthyosaur life history. Understanding their diet, life cycles, and body plans, it is safe to say that Ichthyosaurs would have been comfortable in groups and that it was probably normal for the animals to exist in some sort of social structure akin to, and we may even call it, a pod. Such a grouping of animals would have allowed for cooperative rearing of young, hunting, and defensive strategies which would keep the group alive.

©Raul Martin (via National Geographic)

One such strategy, of course, would have been safety in numbers. Against smaller predators, or perhaps similar sized predators which attacked in groups in a similar manner to the Ichthyosaurs themselves, a group showing aggressively and posturing, would allow for a coordinated defense that would either end up in a physical struggle or one side or another backing down escaping to the best of their ability from what we would consider the victorious side. Against a larger predator, such as this Thalattoarchon saurophagis, which is actually a more basal Ichthyosaur from as early as the Triassic; it kind of makes the image of it hunting down its more "advanced" cousin ichthyosaurs fairly humorous. However, considering that Ichthyosaurus was a numerous and highly successful genus by the time of the mid Jurassic it would have been a hot meal item for any larger predator and, the safety in numbers strategy partly states that one death can save many lives.

Remembering Mary

©Heinrich Harder

In the early 19th century, 1811, Joseph and Mary Anning, young adults of Lyme Regis, Dorset, England, were exploring their world when young Joseph turned up a rather fish-like reptilian skull. A little less than a year later Mary discovered the rest of the skeleton and Ichthyosaurus, along with Mary Anning (but not so much Joseph), became one of the more important paleontological discoveries of the early 1800's; though she did not gain much notoriety until after her 1847 death. Mary Anning is typically remembered as the woman that discovered the first Plesiosaurus (which was described concurrently with Ichthyosaurus in 1821), and she is, but before that, the first skeleton she ever found, was of the Jurassic "Fish Lizard" Ichthyosaurus communis; described and properly named as a genus in 1821 by De la Beche and Conybeare and first described as a species in 1822 by Conybeare. Ichthyosaurus, as a genus, is comprised of four species; I. communis Conybeare, 1822; I. intermedius Conybeare, 1822; I. breviceps Owen, 1881; I. conybeari Lydekker, 1888. There is a lot of interesting history surrounding Ichthyosaurus and, despite the fact that this is a European fossil and not a fossil of the Western Interior Seaway (as the rest of this special month has been), it is a very important marine reptile that was reptilian king of the sea before some of the WIS inhabitants had even begun evolving, as we shall see in the next week. 

The typical Ichthyosaurus, to give shape to the animal before we do a lot history or behavior, would have been about 6.6ft (2m) long tip to tail. It would have been fairly fast as its dolphin shaped body suggests and probably hunted squid rather than fast fish. Integument impressions from German fossils suggest that Ichthyosaurs had large dorsal (back) fins and a fairly large caudal (tail) fin to propel it through the water. It had large sensitive eyes and sensitive ears as well, breathed oxygen through lungs, not gills, and some fossils even suggest viviparity (live birth) among Ichthyosaurs. Ichthyosaurs were most likely very graceful swimmers very in tune with their environment, some of the first highly successful reptiles to transition back to, and dominate, the ancient oceans.

Turtle's Last Hurrah

Despite the respectively "vast" amount of material that exists for Toxochelys there is not a lot of popular mention of them. We have, of course, shown places that they can be found (in part thanks to the highly informative comments of readers) and we have also looked at some well written papers, both old and new, that describe the genus and species within the genus. There are no toys or television shows, no zoo tycoon models that I have seen. The popular Toxochelys just does not exist as we would like it to. Someone did try to patch it into a card game like Dinosaur King, but I do not think that has officially happened as yet. It has been "pinned" on Pinterest, for what that is worth in the current internet culture. Some books also mention Toxochelys, though there are no dedicated texts that I have found. These books are largely about marine reptiles (edited by Jack Callaway and Elizabeth Nicholls) and a reference is made in a book regarding sea turtle behavior and life cycles. Tomorrow we will start a week on a much more popular marine reptile. They are a bit older and we have to venture out of the WIS to visit them, but they are instantly recognizable and I could not do a special topic series like this without mentioning them.

Rocky Mountain Turtles

The Rocky Mountain Dinosaur Resource Center (RMDRC), aside from being a mouthful to say, houses a Toxochelys discovered by Mike Triebold in 1993 in Lane County, Kansas. Lane County is in the western and central area of Kansas, near to Colorado, and the stratigraphic layer from which Triebold's Toxochelys was extracted is Niobrara Chalk approximately 83 million years old, according to the RMDRC. Considering the age of the post, nearly 2 1/2 years ago now, I do not know if the RMDRC still holds Triebold's skeleton or a cast, but it is, of course, a possibility and anyone planning a dinosaur trip in Colorado, regardless of the status of housing for this particular Toxochelys ought to still go to the RMDRC. It is worth noting that this skeleton represents a juvenile turtle (the shell is 9.5in (24cm) long) also, a true rarity for two reasons: 1) Juvenile fossils, despite high mortality of young animals of all extant and most likely extinct species as well, are still considered quite rare in the entire fossil record and 2) Juvenile turtle fossils in particular are rare within the realm of juvenile fossils of any kind due to the fact that they were most likely, at this size, swallowed and digested pretty much entirely. Depicting a growth series in the genus, if not in any one species, is also of great help in understanding the ecological role of these turtles.

In that respect, I have seen some sources claiming that these turtles munched on sharks and other large fish. I think that that is a unique and incorrect view, as I do not see a turtle like this either surprising or chasing down a shark let alone chomping into one and holding on long enough to kill it then ingest it. I suppose strange enough things have happened in nature, but I am not inclined to agree that this happened as a regular occurrence, regardless. More likely this turtle ate squid and/or marine vegetation.

Some Good Papers

I have a number of papers I enjoyed this week. The first is O.P. Hay's long communications in the American Natural History Bulletin. The title was "A Revision of the Species of the Family of Fossil Turtles Called Toxochelyidae, with Descriptions of Two New Species of Toxochelys and a New Species of Porthochelys." In this longer paper Hay does exactly what he says he is going to do, so it is not a big mystery where he is going, but it is a good read to see what his revisions were and how he went about describing the new species. The second recommended reading for the day is, should it be available for everyone's perusal (not everyone can read Taylor and Francis hosted JVP articles), is a good Elizabeth Nicholls paper on new material and another, more recent, revision of the genus Toxochelys. Her revision, and description of Niobrara material, extends the stratigraphic range of the genus. Matzke's "Osteology of the skull of Toxochelys" looks like an interesting read, but I can only get a short preview PDF, so I cannot comment on it too much. I would be interested in it though; it is the kind of thing I enjoy reading. That wraps up my recommended reading for the day. If anyone else has any good suggestions, please share them!

Welcome To A Lack of Videos

Searching for videos of Toxochelys turns up a wealth of 3 whole videos that mention Toxochelys; one of these does not even have anything to do with the turtle, so it is pointless to share. One of the videos is a video of the newer Houston Museum of Natural Science's display within the new paleo hall, so that is nice but it is not something we have not seen. The other is a student's presentation from January 2011. It is a little late to add constructive criticism, however, constructive comments, and not bashing the young lady that created the short presentation (there are a few things wrong but we all know I have made mistakes here as well!)could not hurt others creating similar presentations in the future!

I found this nifty little number in an image search. It was hosted on Scoopweb. There are no real coloring pages that are specifically supposed to be Toxochelys turtles and there are also no cartoons or computer graphics kid shows. As such, this is a very short entry today, sadly. Therefore, enjoy this Sunday and relax after reading a little bit about Toxochelys.

That Eerie Smiling

I have yet to find a turtle skeleton that does not seem to have some degree of perpetual smile. Snapping turtles maybe, they scowl when alive so it is a good bet they do as skeletons, but certainly not Cretaceous turtles like Toxochelys. The Tylosaur chasing it would never be accused of smiling and the fact that it is being chased and still has that perpetual smile on its skeletal face almost makes this exciting chase scene seem exceedingly ludicrous. However, happy turtles, whether being chased or not, make me happy, and I therefore endorse the happy facade of the endangered turtle. We all know in reality that, with knowledge of the ambush from behind that the surge of water has certainly given the turtle, it would be wide-eyed and paddling as fast as its little paddling feet could go. The hard shell of an older adult would probably go a great way toward deflecting and deterring a mosasaur from trying to eat the turtle, but juvenile mosasaurs or desperate adults would probably still attempt to bite into this hard target.

Paintings and other illustrations of Toxochelys, while the most populous turtle fossil in Kansas, are rare even in Kansas. However, we do have some fun, and scary if the prior image is included, scenes acted out by skeletons in museum displays. The availability of the skeletal material for full recreation and casting allows for more interested museums to possess displays, though obviously Toxochelys is not the most often displayed fossil in the country. Thankfully those that do use it for display have done so in fun ways. The chase scene before between potential predator and prey is like a scarier version of this turtle chase scene. The number of reasons for solitary animals like sea turtles to chase one another is minimal, so, were this to be evidenced by fossils or witnessed in the wild the assumptions would probably pool down to 1) mating season or 2) territorial encounters. Considering most sea turtles of this time would probably have been wandering animals "territorial encounters" is probably less feasible, but considering we cannot watch these animals interact, anything could be true honestly!

Toxic Shells?

Discovered at Keystone Gallery

Toxochelys is a sea turtle genus. There have been a few sites that have compared the genus to Loggerhead turtles and a few that have compare it to modern Green sea turtles. I like the Green sea turtle comparison personally. The shells of the Toxochelys turtles, there are four species in the genus- T. bauri, T. browni,T. latiremis, and T. weeksi- are much more solid, and therefore heavier, than other Cretaceous sea turtles of the Western Interior Seaway. Archelon, if we remember, had a strutted carapace that had either stretched leather or dermal/osteo scuting that has since been lost or simply not preserved with any discovered fossils. The carapace of the Toxochelys turtles, however, was only semi-strutted with a solid carapace shelf extending from the midline laterally and covering approximately half of the dorsal shell area of the adult turtle. Scutes around the edge of the shell border were also thicker than those we see in Archelon specimens. The enhanced defensive capabilities of these shells and the spreading of multiple species of turtle within the genera show that this was a successful turtle. In fact, Toxochelys constitutes the most often discovered genus of turtle, with one species, T. latiremis, accounting for many of those specimens, in the state of Kansas; another qualified testament to their prolific populations. The average Toxochelys was about 6ft (2m) long with an estimated mass of approximately 23.1lbs (10.5kg); weight estimates were based on a 17 x 18 inch (44 x 45cm) carapace average.

Sharks and Being Popular

Cretoxyrhina, as we have seen, is a popular shark in documentaries, on kid's shows, as fossil remains, illustrations, and the subject of papers and books. Now we can add toys to that list, of course we expect to see toys coming out of any children's show and PBS' Dinosaur Train is no exception. Safari chimes in though as well with one of their small TOOB figure sets, so the only toys available are not necessarily extra cartoon-like like the Dinosaur Train toys. Strangely enough, however, Cretoxyrhina has not really made a lot of headway in the video game department. It has been modded into Zoo Tycoon, but no one has created, to my knowledge, any in the Spore creature creator. In fact, we have not seen a single sea creature that I can remember come from Spore, which is odd for popular Thursdays. To finish the popularity splurge, I would like to offer everyone the ability to purchase their very own Cretoxyrhina mantelli life size replica:

Available at http://www.dinocasts.com/ for only 18,000Eur ($23,437)

Teeth of A Killer

©Mike Everhart (he notes that this is a "small part" of his collection)

As noted previously, the teeth of Cretoxyrhina are one of the most common preserved elements of the shark. There are, of course, various reasons for this happening. One reason, and probably the biggest reason, is the positive bias of the fossil record concerning mass of material. Though one tooth does not constitute much mass, the constant shedding, replacement, and cycling of teeth in the well known shark conveyor belt type fashion within the jaw, over time, amounts to an impressive amount of dental mass over the life of a single shark that becomes available for preservation. These massive amounts of teeth allow for the fossils to be discovered all over Cretaceous Kansas soils; it is likely that any given road cut (land sliced through to provide surface area for paved or dirt roads) regardless of size possesses at least a single tooth somewhere along its face. Considering Mr. Everhart has discovered an impressively large number of the teeth and that those before him collected large numbers of teeth, a legacy of shark tooth collection by both private and public collectors since the 1870's at the very least exists in written records, we know that the shark population in the Kansas waters was impressive and that each of those animals shedding probably thousands of teeth over their lifetimes means that, despite the enormous amount of teeth discovered, there are potentially millions more just lying around in Kansas and other states with Cretaceous soils exposed. If any of you ever go to the Midwest US for vacation, ask permission, and look for shark teeth! I would say look for some in a souvenir shop, but apparently there was a big to-do about selling fossils in the last 20 years or so in Kansas and the likelihood of finding genuine fossil teeth for sale is minimal at best. That just means, with the landowner's permission, you have to do the work yourself if you want genuine Cretoxyrhina teeth for your personal collection; again, some people frown on personal collections of fossils, I am pretty much neutral on the subject however.

Shimada Loves Sharks

While we happened to have a lot of information and input on Tylosaurus and Xiphactinus from Mr. Everhart, and he does have quite a bit of research behind him on Cretoxyrhina as well, the researcher to highlight with papers today is Kenshu Shimada. Mr. Shimada has done quite a lot of work on Cretoxyrhina. In fact, searching Google scholar, of the first 10 results that appear 7 are papers authored by Shimada. I think we could safely call him the "Cretaceous Shark Guy" without offending him. His research has hit a myriad of topics in the world of Cretoxyrhina including skeletal structure, life history, and even the ecology of the animal. I honestly would recommend skimming the discussions and results sections, at least, of some of his papers to get a better understanding of Cretoxyrhina and the world it lived in. There are a surprising number of papers written about this shark. My favorite, however, is the paleoecology paper from 1997. The reason I say this is my favorite is because of the "whole picture" frame that Shimada paints of the world of Cretoxyrhina. I like the image of the shark in its environment.

Cretoxyrhina Lies Under the Ocean

A small National Geographic vignette on a few of the animals featured in their Sea Monsters movie displays and briefly discusses Cretoxyrhina, presenting some concise facts about the animal. The model is heavily influenced by the body of the great white shark.

Discovery's Monsters Resurrected (also called Mega Beasts) pitted Cretoxyrhina against mosasaurs; it was very non-descript in discussing which mosasaur was being presented from the clips I have seen but I am willing to bank on Tylosaurus. Cretoxyrhina is referred to as "Ginsu Shark" throughout the episode as well, but we can chalk that up to the "sexiness" of the name compared to Cretoxyrhina.

Carla and Some Kid Friendly Facts

From Wikimedia Commons

There are a few pages that have child friendly facts. I think the most concise and one of the better ones is the National Geographic page dedicated to Cretoxyrhina within their larger Sea Monsters set of pages. There is also the Dinosaur Train "Field Guide" about Cretoxyrhina. The entry exists because there was an episode of Dinosaur Train dedicated to Cretoxyrhina (I am not the only "dinosaur dedicated" science outlet that talks about non-dinosaurians!); that would be episode 38 of season 1 according to the internet but episode 36 of season 1 on Netflix. The size comparison image, which would make a good coloring page if printed out, was placed on Wikimedia by a user called Mononykus, but without a user profile I cannot credit it better than that.

The Changing Shark Body Plan

©Tuomas Koivurinne

Cretoxyrhina was not always a bloodthirsty hunter. As happens in nature there were probably times like this one in which great hunters such as Tylosaurus and Cretoxyrhina crossed paths without attacking one another or the schools of fish that are lazily swimming around them. It was probably not often, but it more than likely happened at least once in the history of the Western Interior Seaway. One of the more exceptional characteristics of this piece is actually the symbiotic nature of the small fish attaching themselves to both the upper Tylosaurus and the Cretoxyrhina. In modern times remoras would be the fish holding on to that niche in the ocean ecology, however, we do not necessarily know that there was a fish living symbiotically with these sharks or that they would have been remoras if there were sharks living alongside smaller symbiotes at that time. Sometime in the future, perhaps, a great find will come along that proves or disproves this, but it is a very interesting modern relationship shown in an ancient system.

©Dmitry Bogdanov

The overall shape of Cretoxyrhina, along with many other extinct cartilaginous fishes, is subject to interpretation due to the lack of well ossified, and therefore fossilized, bits and pieces of cartilaginous fishes. Teeth and sometimes jawbones themselves do fossilize, but these are the better examples of what bits and pieces we do unearth that are related to Mesozoic sharks. Teeth and jaws allow for size extrapolations based on modern sharks' ratios between tooth/jaw size and body size, but the overall shape, as with so many other prehistoric animals and previously stated, is open to the interpretation of the illustrator. In that vein, searching for images of Cretoxyrhina pulls up bulldog nosed images such as this based off of bull sharks, longer nosed animals based off of mako shark body types, and of course, there are images, look at yesterday's image, based off of the great white shark body type.

©Dmitry Bogdanov

Dmitry Bogdanov did a great job of showing two of those body types previously discussed in his art featuring Cretoxyrhina. The first version, the bull shark-esque and short nosed version previously noted, is well done considering that body type. The body type in this image is much more related to the great white body plan while the background Squalicorax are closer to  the bull shark body plan. Regardless, the Squalicorax and Cretoxyrhina alike are highly interested in the bloated, floating dinosaur carcass; as any good scavenger or opportunistic feeder would be when a free meal simply floats out to sea somehow. It appears, in this image, that a pecking order is about to be established amongst the scavengers, or that the feeding frenzy is just about to start between these three sharks and potentially more lurking in the shadows or moving in from off in the distance.

Ginsu; Not Just Knives

©Dan Varner (It is also the cover image of Oceans of Kansas)

When I was planning out February and March back in late November I knew that my birthday would fall in one of these weeks and I also knew that juxtaposing bony and cartilaginous fishes ("fishes" still sounds funny to me even though I have accepted its usage) would be beneficial for the reading audience. Bearing those two things in mind I decided, though I am a big fan of plesiosaurs and mosasaurs as well, that I would place one of my absolute favorite genera that I wanted to cover over my birthday week. Place the bony fish prior to the cartilaginous fish just made sense to me. Therefore, following the bony fish, and voracious eater, Xiphactinus, we see here the powerful and frightening shark Cretoxyrhina mantelli biting into a juvenile Tylosaurus.

Cretoxyrhina was an Early to Middle Cretaceous shark, nicknamed the "Ginsu Shark," which reached lengths of approximately 20 feet (6.1m); it is difficult to estimate weight of fossilized cartilaginous fish and as such, I do not recall seeing any confident estimates of weight for Cretoxyrhina. The jaws of the Ginsu Shark were, like sharks today, a veritable death chamber with 34  upper and 36 lower teeth approximately 6 inches 6cm long (brain cramp, my apologies) lining the great mouth of the shark. This week ought to be a true Jaws story in the making, and I am working to procure permissions for some great art to share over the week, so stay tuned; it is basically Cretaceous Shark Week here folks!

References for today:
Everhart, Mike. "A GIANT GINSU SHARK (Cretoxyrhina mantelli Agassiz) From Late CRETACEOUS Chalk of KANSAS"