Friday, January 30, 2009

Time for a quiz

In between grant writing fury, I thought I'd take a moment to post a picture of a very odd fossil, and see if anyone could correctly identify it.

Some hints: this is from my field area, so it is marine, from central California, and approximately 6 million years old, and it belongs to a vertebrate. Also, it is very incomplete, but there are several features that distinguish it. So - now it is your job (if you so wish) to figure out what it is. And yes, '20 questions' is okay-ish.

Only one rule: folks who have already seen this can't give it away.

Good Luck!


palaeoptera said...

I know what it is!

J. Velez-Juarbe said...

Interesting!! I've got a some of questions.

Is this from a marine tetrapod?

Is this from a terrestrial tetrapod?

Is the picture on the left a lateral view?

Robert Boessenecker said...

Good questions:

1- no

2- also no

3- no, but the middle picture is

Hope this doesn't make this any more difficult!

J. Velez-Juarbe said...

Thanks for the answers, I'll give it a try then.

Elasmobranchii - fragment of the articular surface of a vertebra.

Robert Boessenecker said...

Good job! Yes, it is a partial centrum of a large elasmobranch. In the case of the Purisima Formation, Carcharocles was already extinct by this point, and Carcharodon is not large enough to produce a 15cm wide vertebra; however, Cetorhinus maximus is extremely common in this deposit (and this bed in particular), and it likely belongs to Cetorhinus (otherwise known as a basking shark for all you non-shark folks out there).