2. A fossil mosasaur, an aquatic relative of lizards, from the Late Cretaceous Period, 86 million years ago;
3. A fossil ichthyosaur, a dolphin-like reptile, from the Early Jurassic Period, 190 million years ago.
|From top to bottom: sea turtle, ichthyosaur, mosasaur, now drawn in|
evidence-based living color!
Most good features of an organism have more than one purpose, so camouflage and heat-absorption are both likely good explanations. One way or the other, this trio of ancient sea-goers can now join the ever-growing list of prehistoric animals that can be drawn in color with real evidence to back it up!
|The prehistoric 'spoonbill' shark,|
This time, we’re stopping to visit a prehistoric shark called Bandringa. Bandringa lived during the Carboniferous Period, had a ‘spoonbill’ similar to a modern sawfish, and apparently raised its babies in Illinois.
Bandringa fossils have been found at three fossil sites in Illinois, Ohio, and Pennsylvania. Past studies have identified two different species of this shark: B. rayi and B. herdinae. A recent study by Sallan and Coates (2014) took a close look at all of these fossils, and found two surprising things:
Second, it looks like all of the Bandringa fossils from the Illinois site are young sharks, while the Ohio and Pennsylvania fossils are all adults. Also interesting is that the Illinois site was formed in an ancient river delta – where a river emptied into the ocean – while the Ohio and Pennsylvania sites both represent upstream parts of the ancient river. Coincidence? These paleontologists think not.
It looks like Bandringa may have done something similar, but in reverse, giving birth in the estuarine (freshwater + saltwater) environment of the ancient Illinois delta, then swimming upstream to live its adult life in the prehistoric freshwater rivers of Ohio and Pennsylvania. On top of finding all the juvenile sharks living in the estuary, the researchers also found fossilized egg casings which may have belonged to Bandringa, or possibly to other fish also using this site as a nursery. Not only does this give us some really remarkable insight into the life of this prehistoric shark, but this is also the oldest evidence of shark migration!
|Callorhinchus milli, the Elephant Shark or|
Australian Ghost Shark. Adorable.