Matanuska Formation

[3][4] The lower Matanuska Formation (MF) is several hundred meters thick and includes nonmarine and marine sediments.

[5] In 1994, excavations for road material uncovered a hadrosaur specimen near the Glenn Highway, approximately 150 miles northeast of Anchorage.

[25] The location of the specimen makes it significant as a biogeographic link between the hadrosaurs of North America and Asia.

[25] Their examination of the specimen found the "Talkeetna Mountains Hadrosaur" to be a juvenile animal about 3 m (10 feet) long.

They determined that the specimen formed from the remains of a hadrosaur carcass that had bloated with gasses and been washed out to sea.

[29] The associated heteromorphic ammonites and inoceramid bivalves indicate that the Talkeetna Mountains Hadrosaur was buried at a depth greater than 35 m.[30] The body came to rest on its left side with limbs outstretched.

However, none of the teeth belonging to the fishes preserved in the Matanuska Formation fit the size or arrangement of the bite marks.

[34] Nevertheless, the size, spacing, and shape of the marks were similar to those of teeth from the mosasaur species Tylosaurus proriger.

[33] The largest parts of the animal would have been too large for the scavenging mosasaur to completely wrap its jaws around, and these are the areas around which the concretions formed.

[33] The size, spacing, and shape of apparent bite marks on the bones of the Talkeetna Mountains Hadrosaur were similar to those of teeth from the mosasaur species Tylosaurus proriger, suggests that some similar animal swam in the waters of the Matanuska Formation's depositional environment.