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Xiphactinus For Kids

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Name:

Xiphactinus (combination Latin and Greek for "sword ray"); pronounced zih-FACK-tih-nuss
X. audax
X. vestus

Habitat:

Shallow waters of North America, Europe, Australia

Historical Period:

Late Cretaceous (90-65 million years ago)

Size and Weight:

Up to 20 feet long and 500-1,000 pounds

Diet:

Fish

Distinguishing Characteristics:

Large size; prominent teeth
 This week we have an awesome coloring page, all things considered, of Xiphactinus. Today is an easy day. Share the facts, color the mean looking fish, enjoy some snow outside (if you have it)

Swimming with Xiphactinus

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As has been mentioned in some of the Facebook posts (not necessarily on the blog posts) National Geographic's Xiphactinus is not spectacular due to television standardization; meaning sometimes the science gets sidelined by showmanship for interest purposes. However, almost every television show in existence has ignored facts here and there as it pleases them in order to air a show which will generate interest. This is a paradox that we have seen many times in looking at documentaries through our dinosaur vision, so we are used to it to a point; should the show be entertaining at the sake of some scientific fact or should it contain only scientific fact at the sake of entertainment? Entertainment purposes may generate scientific interest where lack of entertainment may cause people to "tune out" and all the science in the world may be wasted on having an effectively non-existent audience. It is a wrestling match as old as documentaries themselves. Regardless, I have two videos to share today, neither of which is a full scale documentary (more on the two documentaries which feature Xiphactinus on Thursday this week).

One shows a proposed swimming posture of Xiphactinus, which appears a bit rigid as far as I am concerned.

The other is a short documentary on the exhibit of Xiphactinus at the Hastings Museum in Nebraska.

Fish of Many Letters

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My favorite papers are always the older papers, with rare exception. It is not because I am a traditionalist or that I find current science to be less educated or informed, it is totally the language used. Scientific papers are dry by nature, something that will probably never change, but the language of the earlier paleontologists is from a different time and, in my opinion, makes the reading that much more interesting despite its dry nature. With that in mind, I picked out two papers- out of a virtual stack not to mention a good portion of Oceans of Kansas' chapter on fish- one of which is from 1997 and the other 99 years older, from 1898, that redescribes and makes new observations on Xiphactinus.

The 1997 paper, by Schwimmer, Stewart, and Williams, discusses the different Xiphactinus discoveries in North America and the distribution of the species Xiphactinus vetus in the Eastern US. The paper is a short communication and thus is not very highly in depth, but it does address some questions of distribution and poses a question near the end of what kind of evolutionary relationship existed between the two species of Xiphactinus.

The older paper, O.P. Hay's 1898 observations and redscription, does exactly what it says it is going to do; Hay makes observations on Cope's and Leidy's  two "distinct" genera of fish. Hay goes on to talk about multiple species but does make an important note that Cope's genus, Portheus, and Leidy's genus, Xiphactinus, possess "no serious discrepancy between Cope's description of his Portheus thaumas and my specimen [Leidy's Xiphactinus]." Additionally, as has been made often here, Hay compares Xiphactinus with extant tarpon regularly throughout the paper. It is a fairly good read.

Xiphactinus The Swallower

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As mentioned previously, the gluttony of Xiphactinus has been to our benefit as a paleontologist community. Finds of Xiphactinus that are fully articulated tend to be quite often associated with other animals stuck in their gullets. There have been plenty of other finds that are simply heads or fins, teeth are popular also, and these remains can be distinguished from other members of the family (Ichthyodectidae) to which Xiphactinus belongs primarily by the fact that Xiphactinus is simply a larger fish than other members of the family (the genera Gillicus and Ichthyodectes). In addition to whole monster fish discovered with stomach contents, or throat contents in some specimens that died while eating, and scavenged remains, there have also been a few Xiphactinus remains discovered as stomach contents themselves in the bellies of larger predators such as the shark Cretoxyrhina; Cretoxyrhina teeth have been discovered in Xiphactinus vertebrae also. Being the largest fish in the sea, the largest bony fish at least, allowed for fairly good preservation and thus discovery of Xiphactinus specimens over the past 150 years in Kansas, in particular, and the remainder of North America that was covered by the Western Interior Seaway.

A Positive Bias Fossil

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Bias in the records, rock and fossil, are always of paramount concern to paleontologists and a positive bias, while not always a good thing, is far more welcome than a negative bias typically. Xiphactinus has been discovered in so many places, pieces, and configurations that it is a small but massively important positive bias center of the fossil record. This translates into a fairly large impact on popular culture. Xiphactinus appears in two major documentaries, Walking with Dinosaurs: Sea Monsters and Sea Monsters, as well as in video games such as Zoo Tycoon; it has been modded in. In true human/prehistoric animal interaction as seen with other Nigel Marvin/WwD BBC shows, Xiphactinus attempts to attack a person. At least the model used was fairly accurate though if not the premise of the episode. The Sea Monsters National Geographic movie is best described as a documentary that possessed highly qualified and wonderful technical/scientific advisers, but fell victim, in parts, to the Hollywood bug; as explained earlier this week by Mr. Everhart in response to a still from the movie "We tried to get the producer to NOT use the schooling X-fish scene... but he was after a dramatic effect, not scientific accuracy."

Xiphactinus does show up in collector's collections as well as statues and smaller figures. There is also a lot of artwork that features Xiphactinus; a simple Google image search or even going straight to a site such as DeviantArt and searching for Xiphactinus will show a rather long list of illustrations and paintings; some of which are fantastically beautiful.

Ginsu; Not Just Knives

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©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"

The Changing Shark Body Plan

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©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.

Carla and Some Kid Friendly Facts

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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.

Cretoxyrhina Lies Under the Ocean

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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.

Shimada Loves Sharks

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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.

Teeth of A Killer

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©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.

Sharks and Being Popular

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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)

Toxic Shells?

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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.

That Eerie Smiling

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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!

Article 1

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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.

Welcome To A Lack of Videos

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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!

Some Good Papers

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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!

Rocky Mountain Turtles

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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.

Turtle's Last Hurrah

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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.

Remembering Mary

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©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. communisConybeare, 1822;I. intermediusConybeare, 1822; I. brevicepsOwen, 1881;I. conybeariLydekker, 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.
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