Saurodon's chin spike

[Anthony]

Query on one of the rarer fish in the Niobrara. Saurodon posesses a large extremely pointy predentary. What was its purpose? Offensive or defensive?

[Mike]

Ummmm......danged if I know




Although Charlie Sternberg (and others of his time) would have argued that Saurodon (and later genera, Saurocephalus and Prosaurodon pygmaeus) were swimming around, stabbing and slashing with their pointed chin... it's difficult to make a case for a medium sized fish using a short spike on the lower jaw to defend itself or to injure prey. It had saw-toothed upper and lower jaws with

sharp, blade-like teeth that were more than adequate for seizing smaller fishes. 











We need to find a Saurodon skull stuck through the ribs of a larger ichthyodectid..... where both died in an epic struggle to the death... 

More info here:
http://www.oceansofkansas.com/Saurodon.html

Regards,

Mike

[Anthony]

I could just see Sternberg's description now, with a Saurodon and Protosphyraena battling, being finished off by a Portheus....

I found my first Saurodon about 30 minutes before discovering Cap'n Chuck, the big predentary spike has always intrigued me.

[Mike]

The chin spike is certainly an interesting feature...

While doing my Oceans of Kansas book, I was able to visit the collections of the Academy of Natural Sciences of Philadelphia (mostly to look at the type specimen of Elasmosaurus platyurus...)

I was also able to see and photograph the type specimen (and only remaining fossil brought back by the Lewis and Clark expedition, 1804-1805)...

It was collected from the upper Niobrara Formation on the banks of the Missouri River in northwestern Iowa and later described by a Dr. Richard Harlan (1824) as the jaw of a reptile, Saurocephalus lanciformis...



Of course it wasn't a reptile.... but rather the upper jaw of a fish closely related to what would eventually be called Saurodon leanus Hay 1830. Although Hay recognized that the two genera were related, he tried to avoid further confusing his fish with Harlan's "reptile."

It was another example of Harlan's classic mistakes (e.g. "Ichthyosaurus" missouriensis (1834) = Mosasaurus missouriensis and Basilosaurus (1834)... which is not a reptile, let alone the "King Reptile" - it is a primitive whale)...

More here:
http://www.oceansofkansas.com/Saurodon.html
Regards,
Mike

[Piper]

Is it possible that this animal used its chin spike to gather prey from the soft bottom of the sea, such as small rays?

[Mike]

I think that is one of the more plausible explanations... although we have very little evidence of what kind of prey that it might have been feeding upon... For the most part, the bottom muds of the chalk portion of the Western Interior Sea appear to be pretty low in diversity .... mostly just a few species of large inoceramid bivalves and the epizoans that were attached to them. The blade-shaped teeth of Saurodon and Saurocephalus appear to better adapted to feeding on pelagic prey (e.g. fish and squid).

Anthony needs to find us one with gut contents!

Mike   

[Anthony]

It's hard enough just finding ones with more than just head preserved...

There were echinoids in those muds, but I agree with Mike about the tooth shape being better suited for fleshy prey.