And now for a rare one: Martinichthys

Even though the past two (hot) expeditions to Kansas have been primarily aimed at recovering various Xiphactinus skeletons that we have discovered over the years, we did have a little time to scout some outcrops low in the Niobrara chalk. Last Monday, I stumbled across some fish skull parts on an outcrop and followed them up to their source. This is what was coming out:

The rostrum of this rare fish is the most commonly discovered part recovered, mostly because it is the densest and most durable bit, and most likely to be found after weathering out of the outcrop. The teeth are tiny and resemble small barbs, though they number in the thousands. We may have found postcranial material with this fish as well, and a recovery operation at the site will be attempted next time we go to Kansas, though that may be a few months.

Martinichtys seems to have gone extinct between Marker units 5 and 6 (this specimen is the highest one I can find data for, about 1m below MU 6), as do several other animals int he Niobrara (such as Thryptodus, Tylosaurus kansasensis, and several invertebrates). I am curious what happened to wipe these species out.