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Ages of the Earth => Dinosaurs => Topic started by: Melody Stacker on April 26, 2008, 03:47:02 pm



Title: the Prehistoric Ocean: Illustrations of Dinosaurs
Post by: Melody Stacker on April 26, 2008, 03:47:02 pm
(http://www.search4dinosaurs.com/miller_mosasaur.jpg)

Mosasaur


Title: Re: Illustrations of Dinosaurs
Post by: Melody Stacker on April 26, 2008, 03:49:24 pm
(http://www.search4dinosaurs.com/devonian.gif)

Devonian Scene

http://www.search4dinosaurs.com/


Title: Re: Illustrations of Dinosaurs
Post by: Melody Stacker on April 26, 2008, 03:51:22 pm
(http://www.oceansofkansas.com/Varner/varnr22b.jpg)

http://www.oceansofkansas.com/varner.html


Title: Re: Illustrations of Dinosaurs
Post by: Melody Stacker on April 26, 2008, 03:52:32 pm
(http://www.oceansofkansas.com/Varner/varn16.jpg)

Here a large Tylosaurus is about to make lunch of a smaller mosasaur called Halisaurus sternbergi.  Like their modern relatives, the snakes, mosasaurs were capable of swallowing large prey whole because of the unique design of their skull and very flexible lower jaws.


Title: Re: Illustrations of Dinosaurs
Post by: Melody Stacker on April 26, 2008, 03:53:40 pm
(http://www.oceansofkansas.com/Varner/varn13.jpg)

Although Hesperornis was a large and very successful marine bird, it was no match for something as large (and hungry) as a Tylosaurus.  This picture is loosely based on the discovery in South Dakota of a Tylosaurus with fossilized stomach contents that included a fish (Bananogmius), a smaller mosasaur (Clidastes) and a bird (Hesperornis).


Title: Re: Illustrations of Dinosaurs
Post by: Melody Stacker on April 26, 2008, 03:55:24 pm
(http://www.oceansofkansas.com/Varner/varn14.jpg)

Mosasaurs probably fed mostly on fish, although some varieties were specialized to the point of feeding on soft bodied squid or even clams.  Here a Platecarpus grabs an unlucky Enchodus.... the "Saber Toothed Herring" of the late Cretaceous seas.


Title: Re: Illustrations of Dinosaurs
Post by: Melody Stacker on April 26, 2008, 03:56:13 pm
(http://www.oceansofkansas.com/Varner/varn15.jpg)

Here a polycotylid plesiosaur bites at the front paddle of another member of the same species.  Like many of other Dan's works, this picture was based on an actual fossil.  A polycotylid specimen found in South Dakota had a broken plesiosaur tooth embedded in the bones of   the paddle.  How it got there is conjectural, but Dan's painting shows what could have happened.


Title: Re: the Prehistoric Ocean: Illustrations of Dinosaurs
Post by: Melody Stacker on April 26, 2008, 03:58:53 pm
(http://www.oceansofkansas.com/Varner/varner18.jpg)

A pod of Cryptoclidus plesiosaurs (late Jurassic, Europe) cruises near the surface in search of prey. These animals reached lengths of about 4 meters. Large numbers of slender, inter-meshing teeth in their jaws made them very efficient in catching small fish.


Title: Re: the Prehistoric Ocean: Illustrations of Dinosaurs
Post by: Melody Stacker on April 26, 2008, 04:00:10 pm
(http://www.oceansofkansas.com/Varner/varner20.jpg)

A nothosaur (early to late Triassic) prowls the shallow sea for food.  These semi-marine lizards reached lengths of about 3 meters.   Their remains are found in many places around the world, including China, Russia, Germany, the Netherlands and North Africa. Instead of paddles, Nothosaurs had webs between their long toes.  See a picture of the cast of small Nothosaur skeleton here.

http://www.oceansofkansas.com/varner.html

http://www.search4dinosaurs.com/


Title: Re: the Prehistoric Ocean: Illustrations of Dinosaurs
Post by: Melody Stacker on April 26, 2008, 04:02:09 pm
(http://www.oceansofkansas.com/Varner/varner21.jpg)

An early and very 'fish-like' crocodile (Geosaurus) swims in the shallow seas covering Germany in the Middle to Late Jurassic. Although not closely related to the ichthyosaurs,  the tails of member of the Metriorhynch family were adapted for swimming in the same way, even to the noticeable down bend in the posterior caudal vertebrae.


Title: Re: the Prehistoric Ocean: Illustrations of Dinosaurs
Post by: Melody Stacker on April 26, 2008, 04:02:52 pm
(http://www.oceansofkansas.com/Varner/varner19.jpg)

Placodus, a placodont from the early to middle Triassic of Europe grubs for clams and other shellfish in the mud of a near-shore sea bottom.  While placodonts fed in the ocean, they probably spent a large portion of their lives on land.


Title: Re: the Prehistoric Ocean: Illustrations of Dinosaurs
Post by: Melody Stacker on April 26, 2008, 07:27:53 pm
(http://www.oceansofkansas.com/Varner/varnr29.jpg)

NEW 2005 - Two very large elasmosaurs (Styxosaurus snowii) cross paths while feeding near the surface in the Western Interior Sea during the early Campanian. Plesiosaurs were rare during the deposition of the Smoky Hill Chalk, at least in part due to the presence of the giant ginsu shark, Cretoxyrhina mantelli.


Title: Re: the Prehistoric Ocean: Illustrations of Dinosaurs
Post by: Melody Stacker on April 26, 2008, 07:29:39 pm
(http://www.oceansofkansas.com/Varner/varnr30.jpg)

NEW 2005 - A five-foot- long Hesperornis regalis swims over the top of a giant Protostega gigas turtle during the early Campanian. The arrival of these two species marked a major change in the fauna of the Western Interior Sea and were probably there as a result of world-wide changes in the Earth's climate.


Title: Re: the Prehistoric Ocean: Illustrations of Dinosaurs
Post by: Melody Stacker on April 26, 2008, 07:30:52 pm
(http://www.oceansofkansas.com/Varner/VARNR26.jpg)

Somewhere in the Western Interior Sea, a giant pliosaur (Brachauchenius lucasi) is about to make lunch out of a small turtle similar to Desmatochelys.  Brachauchenius was one of the last of the pliosaurs and made it's final appearance in Kansas during the deposition of the Fairport Chalk Member (middle Turonian) of the Carlile Shale. Varner painting courtesy of the Museum of Northern Arizona.


Title: Re: the Prehistoric Ocean: Illustrations of Dinosaurs
Post by: Melody Stacker on April 26, 2008, 07:35:35 pm
(http://www.oceansofkansas.com/Varner/VARNR25.jpg)

This picture has an interesting international connection... The painting was done by Dan Varner for the Natural History Museum of Maastricht in the Netherlands as a part of the celebration of the discovery of a large, fairly complete specimen of a new mosasaur species (Prognathodon saturator) in the ENCI limestone quarry outside of Maastricht. Many shark (Squalus) teeth were found in association with the remains, indicating that the carcass had probably been scavenged by sharks after death. I was able to visit the museum in May, 2004 for the First Mosasaur Meeting.  The photograph was made from the original painting at the Maastricht Museum.


Title: Re: the Prehistoric Ocean: Illustrations of Dinosaurs
Post by: Melody Stacker on April 26, 2008, 07:37:27 pm
(http://www.oceansofkansas.com/Varner/varnr23.jpg)

Here a Mosasaurus cruises the rocky underwater shoreline of the Late Cretaceous Japanese Islands, looking for a meal.  The ammonites in the background appear to be wishing they were some place else! During the Late Cretaceous, the ocean off the coast of what would become Japan was host to many different species of ammonites...  and many of the same genera of marine reptiles (mosasaurs and plesiosaurs) as were found in the Western Interior Sea.


Title: Re: the Prehistoric Ocean: Illustrations of Dinosaurs
Post by: Melody Stacker on April 26, 2008, 07:39:14 pm
(http://www.oceansofkansas.com/Varner/varnr24.jpg)

A pod of very early and quite small (1-2 m) ichthyosaurs (Utatsusaurus hataii) searches for prey in the waters near present day Japan.  Some of the earliest remains of ichthyosaurs have been found in Japan and China.


Title: Re: the Prehistoric Ocean: Illustrations of Dinosaurs
Post by: Melody Stacker on April 26, 2008, 07:41:42 pm
(http://www.oceansofkansas.com/Varner/varnr22.jpg)

Here a Mosasaurus hoffmanni just misses the mark in an attack on the marine crocodile, Thoracosaurus, in the seas over present day New Jersey. Wanna bet on the outcome? These Maastrichtian age animals are known from both North America and the Netherlands in Europe (the North Atlantic was much smaller 68 million years ago).  Thoracosaurus survived for some time after the K/T boundary event while mosasaurs, plesiosaurs, dinosaurs and many other groups did not. Although first found in the Netherlands, M. hoffmanni is also known from the Western Interior Sea (Texas).


Title: Re: the Prehistoric Ocean: Illustrations of Dinosaurs
Post by: Melody Stacker on April 26, 2008, 07:43:21 pm
(http://www.oceansofkansas.com/Varner/varner11.jpg)

This rather dramatic picture was done especially for my poster presentation at the 1999 Society of Vertebrate Paleontology meeting in Denver.  It shows a large Cretoxyrhina mantelli shark taking a bite out of a juvenile Tylosaurus.  While we are unsure if these sharks attacked live mosasaurs, or scavenged their carcasses, feeding by sharks on mosasaurs is supported by a lot of fossil evidence. See the Ginsu Shark, Parts and Pieces, and A Moment in Time. 


Title: Re: the Prehistoric Ocean: Illustrations of Dinosaurs
Post by: Melody Stacker on April 26, 2008, 07:44:38 pm
(http://www.oceansofkansas.com/Varner/varn10.jpg)

"Feathers and all" - It's hard to imagine the scale of this picture.... the little swimming birds (Hesperornis) are about 5 feet long and the Tylosaurus ... well, it's huge.  Modeled after the largest specimen on exhibit (The Bunker Tylosaur), this beast was at least 45 feet long and had a skull that was 6 feet in length.  Read about "A day in the life of a mosasaur" here.


Title: Re: the Prehistoric Ocean: Illustrations of Dinosaurs
Post by: Melody Stacker on April 26, 2008, 07:46:28 pm
(http://www.oceansofkansas.com/Varner/varner07.jpg)

In this view, a Clidastes (one of the smaller mosasaurs, about 12 feet long) is about to put the bite on a turtle called Calcarichelys somewhere off the ancient gulf coast of what is now Alabama.   Mosasaurs fed on just about anything that was small enough for them to swallow.


Title: Re: the Prehistoric Ocean: Illustrations of Dinosaurs
Post by: Melody Stacker on April 26, 2008, 07:48:22 pm
(http://www.oceansofkansas.com/Varner/varner.jpg)

This picture shows an attack by a very large (30'+) mosasaur called Tylosaurus proriger on a much smaller Platecarpus mosasaur. Tylosaurus occasionally killed and ate other species of mosasaurs but there is no evidence to show that any of the mosasaurs were cannibalistic toward their own species.


Title: Re: the Prehistoric Ocean: Illustrations of Dinosaurs
Post by: Melody Stacker on April 26, 2008, 07:49:40 pm
(http://www.oceansofkansas.com/Varner/varner01.jpg)

This scene is based on a specimen found South Dakota and shows a mother Plioplatecarpus giving birth to the second of her two babies. Until recently, it was assumed that mosasaurs laid eggs on beaches like turtles. Instead, they appear to have given birth at sea just like the ichthyosaurs. 


Title: Re: the Prehistoric Ocean: Illustrations of Dinosaurs
Post by: Melody Stacker on April 26, 2008, 07:51:01 pm
(http://www.oceansofkansas.com/Varner/varn02.jpg)

This encounter is also based on a recently found specimen of a young adult Mosasaurus conodon that showed evidence (embedded tooth and a broken neck) of being attacked and killed by a larger member of the same species.     


Title: Re: the Prehistoric Ocean: Illustrations of Dinosaurs
Post by: Melody Stacker on April 26, 2008, 07:52:49 pm
(http://www.oceansofkansas.com/Varner/varner03.jpg)

This picture shows a Plioplatecarpus feeding on a school of fish and is based on a specimen found in Central Alabama by a Historical Geology class from Okaloosa Walton Community College in Northwest Florida.  Plioplatecarpus mosasaurs were more advanced and somewhat specialized.  See the latest Plioplatecarpus page - A Plioplatecarpus from North Dakota


Title: Re: the Prehistoric Ocean: Illustrations of Dinosaurs
Post by: Melody Stacker on April 26, 2008, 07:54:54 pm
(http://www.oceansofkansas.com/Varner/varner08.jpg)

Globidens was another very specialized mosasaur, with round, crushing teeth.  This picture shows two Globidens dakotensis mosasaurs feeding on clams and other shellfish found on the bottom of the shallow, inland sea that covered South Dakota and much of the middle of North America.


Title: Re: the Prehistoric Ocean: Illustrations of Dinosaurs
Post by: Melody Stacker on April 26, 2008, 07:57:12 pm
(http://www.oceansofkansas.com/Varner/varner06.jpg)

This picture shows what happens when the hunter becomes the hunted, as a giant pliosaur called Brachauchenius lucasi attacks an early Clidastes mosasaur.  Although pliosaurs became extinct during Turonian time, they were still present in the Western Interior Sea when the first mosasaurs arrived. Even though mosasaurs were top predators, their young were often preyed upon by sharks, large fish, and even other species of mosasaurs.  Life could be short for the unwary.


Title: Re: the Prehistoric Ocean: Illustrations of Dinosaurs
Post by: Melody Stacker on April 26, 2008, 08:02:55 pm
(http://www.oceansofkansas.com/Varner/varner09.jpg)

"Brachauchenius and Squid" from a painting done for Pete Von Sholly. This picture recreates an actual specimen found in the Turner Sandy Member of the Carlile Shale Formation (Turonian / Late Cretaceous) near Edgemont, South Dakota. This was the latest age that these giant pliosaurs were found in North America.... coincidentally the same time that mosasaurs first appeared.


Title: Re: the Prehistoric Ocean: Illustrations of Dinosaurs
Post by: Melody Stacker on April 26, 2008, 08:04:21 pm
(http://www.oceansofkansas.com/Varner/varner04.jpg)

The Cretaceous Seas were a dangerous place for lots of good reasons. This view shows two giant (up to 17 feet or more in length) Xiphactinus audax on the prowl for their next meal.  These fish fed by swallowing their prey whole, and are sometimes found with their last meal perfectly preserved inside.


Title: Re: the Prehistoric Ocean: Illustrations of Dinosaurs
Post by: Melody Stacker on April 26, 2008, 08:05:27 pm
(http://www.oceansofkansas.com/Varner/varner05.jpg)

This picture shows a large (up to 5 feet tall),  flightless seabird called Hesperornis regalis swimming underwater to catch a small fish.   These birds still had teeth in their jaws, but probably behaved much like modern penguins.  Their fossils are much more common in Late Cretaceous marine deposits north of Kansas.