This week’s blog entry is a continuation of last week’s, but I’m going to highlight the non-dinosaur species of the Cretaceous that left fossils in the two state region. Remember, half of this region was under ocean water, so most Cretaceous fossils found here are marine.
I took this photo of a tylosaurus skeleton at the Georgia Southern Museum in Statesboro. Tylosaurus was a large species of mosasaur. Disarticulated specimens are occasionally found in Georgia and Alabama, but nearly complete skeletons are rare. Therefore, this specimen was imported from North Dakota where more complete specimens are more commonly found.
Scientists debate whether mosasaurs were more closely related to snakes or to monitor lizards. They were much like giant replicas of the latter but with flippers instead of legs. At least 4 species swam the shallow seas that inundated what’s now Georgia’s and Alabama’s coastal plain. Tylosaurus, a 40 foot long monster, was the largest and king of the seas, preying on fish, octopus, sharks, plesiosaurs, and other mosasaurs. Plenty of mosasaur fossils bear evidence of interspecific battles. Platecarpus and Clidastes were two other common mosasaurs. Globidens, named for its globe-shaped teeth, fed upon shellfish which it crushed with its specialized dentition.
Illustration of plesiosaur from google images.
The many species of plesiosaurs can be split into two general types: the long-necked and the thick-necked. The long-necked types had ponderous, probably camouflaged, bodies. They quietly swam into schools of fish before their head went into action, snapping left and right to destroy and consume schools of fish. The thick-necked kinds were more active predators resembling mosasaurs in habit.
The Robust Crocodylian–Deinosuchus rugosus
Wow! Look at the size of the skull on this monster. This is a famous photograph of a Deinosuchus skull mounted for many years at the Natural History Museum in New York. David Schwimmer, the leading authority on this species, now writes that this skull was mistakenly reconstructed and the species was not quite this big, but still was almost as large…big enough to kill and eat tyrannosaurs.
I discuss this species more thoroughly in my blog entry, “Shit-eating sharks and fish of the Cretaceous,” from my October archives. The largest crocodylian of all time likely fed upon tyrannosaurs and hadrosaurs, but turtles made up most of its diet. It crushed the chelonians with blunt teeth powered by the the strongest jaw crushing strength in the history of the natural world.
I took this photo of Protostega gigas at the McWane Science Center in Birmingham. It was the largest sea turtle of all time.
Cretaceous turtles are split into two genus: Toxochelyds and Protochelyds.
Ginsu Shark–Cretoxyrhina mantelli
All these shark teeth come from one species. This photo is from the oceans of kansas website.
Scientists named 7 different species based on all the teeth from this single species. Then in 1891, someone discovered a skeleton and found all these different teeth on one animal. The fish is named after the famous knives advertised on late night television.
Armoured fish–Xiphactinus audax
I took these photos of a Xiphactinus audax replica skelton mounted at the McWane Science Center in Birmingham, Alabama.
Photo of a coelacanth from google images.
This ancient species, a real living fossil, predates the age of the dinosaurs. It’s closely related to the ancestor of the evolutionary link between fish and amphibians. Coelacanths originally evolved 400 million years ago–long before dinosaurs evolved. They survived the extinction of the dinosaurs 65.5 million years ago, and still survive today because they’re not good eating for humans who have only been around in our present form for .2-.3 million years.
No Cretaceous age mammal fossils have been discovered in the two state region, but they may have been more common than dinosaurs in the upland areas. They were probably small insectivorous animals, nocturnal in habit. They didn’t live in a situation that would be prone to preserving them as fossils. Dr. Schwimmer has found one leg bone of a Cretaceous bird from the Hesperornidae family. Species from this family grew to 7 feet tall and were wingless, armless oddities that ate fish. Primitive birds may have also been common in the upland areas but perchance didn’t live in a place that would make them likely candidates for fossilization.
Be sure to check the above website out. It’s a fantastic site.