Mosasaur bits?

[lof]

Follow up to my previous post on the mosasaur jaw. Wanted to get my prelim IDs seconded on some other finds. I'm thinking mosasaur teeth--any thoughts on species? Left tooth fragment 3cm long, right tooth 4cm long. Tylosaur, platecarpus and clidastes are possibilities. Can any one point me towards diagnostic marks to differentiate? The other piece I interpret to be a rib (2.5 x 1.5 wide, 10 cm long), with many scavenger shark marks on it. Thanks for your input.

Found near ladonia fossil park, Fannin Co, Texas. Late cretaceous.

[pachy-pleuro-whatnot-odon]

1. The piece of bone is indeed a rib fragment with scavenge marks of sharks on it. Nice find! I've been looking for a piece like that myself for a while now
2. The two tooth fragments are indeed mosasaur in origin. However, as they're partials, it'll be difficult to identify them. That's because the positioning of the carinae plays an important part in identification of individual teeth to genus or species level, as do compression, direction of curvature, and ornamentation. Based on the latter, Clidastes can be eliminated as a possible candidate for the tooth on the right, as that tooth seems to have enamel ridges along the perimeter of the base of the tooth. Typically these tertiary striae would point, instead, to Tylosaurus, and thus T. proriger. However, for a positive confirmation as Tylosaurus, the carinae would have to be positioned in a straight line from one another, whereas they're placed at an offset from one another in Mosasaurus (in this genus, together with the direction of curvature, causing the tooth to look like it has a bit of a twist). In tylosaurine teeth, the curvature in the tooth is moreover restricted to the upper third of the crown, with the direction of curvature being distinctly distal (which contrasts to the mediodistal in Mosasaurus). The tooth on the left, however, without any of these diagnostic features being present, cannot be determined to any genus or species.