Minute Man Fossils
Indeterminate Theropod Premaxillary Tooth-Colorado 001
Indeterminate Theropod Premaxillary Tooth-Colorado 001
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Taxa: Indeterminate Theropoda
Geology: Morrison formation
Age: Jurassic
Locality: Moffat County, Colorado
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Morrison Formation
The Morrison Formation is a widespread sequence of sedimentary rocks from the Late Jurassic period (about 155–148 million years ago) found across the western United States, from Montana to New Mexico. It is composed mainly of mudstone, sandstone, siltstone, and limestone, and is famous for its rich dinosaur fossil beds. These rocks were deposited in river floodplains, lakes, and swamps, reflecting a variety of ancient environments. The Morrison Formation is the most productive source of Jurassic dinosaur fossils in North America.
Morrison fm. Theropods
Small theropods in the Morrison Formation were relatively rare compared to their larger counterparts, with their remains often being fragmentary due to their delicate bone structure. These dinosaurs lived in the Late Jurassic period (about 163.5 to 145 million years ago) across the western United States.
Several taxa of small-bodied theropods have been identified in the Morrison Formation, including Coelurus fragilis, Elaphrosaurus sp., Koparion douglassi, Marshosaurus bicentesimus, Ornitholestes hermanii, Stokesosaurus clevelandi, Tanycolagreus topwilsoni, and various unidentified coelurid theropods. Some fossil evidence also suggests the presence of dromaeosaurid and troodontid theropods.
The scarcity of small theropod fossils is likely due to their rapid decomposition after death, with their remains often being scattered or completely consumed by scavengers like larger theropods and crocodiles. Recent discoveries indicate that the diversity of small theropods in the Morrison Formation was probably much greater than previously thought. These smaller predators likely occupied different ecological niches than the dominant large theropods like Allosaurus, Ceratosaurus, and Torvosaurus, hunting smaller prey while occasionally scavenging from larger carcasses.
