Microvenator

*Microvenator celer*

Microvenator is an extinct genus of caenagnathidae theropod dinosaur that were found in the Cloverly Formation in North America by famous fossil hunter Barnum Brown in 1933 but were never described until 1970 by paleontologist John Ostrom. The fossil found in 1933 was only a four-foot juvenile but they can grow up to three meters long. The adult size of *Microvenator* is estimated to be closer to 10 feet long. Microvenator had long legs and a beak and similar to other Oviraptorids they properly took care of their eggs and young. Since they were small they could fend off smaller prey but larger dinosaurs would be a problem.

## Discovery

Barnum Brown collected the type specimen (**AMNH 3041**) of this animal in 1933. Interestingly, he included what are now known to be *Deinonychus* teeth with the specimen, and thought that his new animal had a small body with an unusually large head. Thus, he informally dubbed it "Megadontosaurus" ("big-toothed lizard"). He had illustrations made of it, but never published the name, a fate shared with several other Cloverly dinosaurs (*Deinonychus*, *Sauropelta*, *Tenontosaurus*). AMNH 3041 includes parts of the skull. hand, foot, left fibula, 23 vertebrae, 4 ribs, and fairly complete ilia, pubes, femora, tibiae, the left ankle, left humerus, radius, and ulna. In 1970 John Ostrom described the type specimen and gave it its formal name. Ostrom also referred a single tooth from the Yale Peabody Museum collection, YPM 5366, to this new species. The illustrations that Brown had prepared were finally published in a detailed and exhaustive monograph by Mackovicky and Sues in 1998. They were unable to confirm that YPM 5366 belongs to *Microvenator*. They confirmed that *Microvenator* is an oviraptorosaurian, and that it is the earliest known member of this group from North America.

## Paleoenvironment

Microvenator fossils are extremely rare, with only the type specimen described, likely due to lack of teeth and frail bones. Microvenator coexisted with notable dinosaurs like Deinonychus, Sauropelta, and Acrocanthosaurus in the Himes Member of the Cloverly Formation.

## JPInstitute.com Description

Microvenator was one of the smallest known meat-eating dinosaurs, and it shows that dinosaurs filled a variety of ecological niches in the Mesozoic. While the giant meat-eaters were hunting and killing the huge plant-eaters, there had to be some small killers to keep the little creatures under control. Microvenator was only about twice as large as Compsognathus , who lived many tens of millions of years earlier.

Very little is known about this small predator. Discovered almost 100 years ago, it was not described until 1970. It has been assigned to a number of different families, including Coeluridae, Maniraptora, Oviraptoridae and Ornithomimidae. It has been reconstructed variously with a large head, feathers and beak.

## Links

https://web.archive.org/web/20031007011243/http://www.jpinstitute.com/dinopedia/dinocards/dc\_micro.html

## References

* Ostrom, John H. (1970). "Stratigraphy and paleontology of the Cloverly Formation (Lower Cretaceous) of the Bighorn Basin area, Wyoming and Montana” Ibid. 35:234pp.
* Mackovicky, Peter J., Sues, Hans-Dieter. (1998). "Anatomy and phylogenetic relationships of the Theropod Dinosaur *Microvenator celer* from the Lower Cretaceous of Montana” American Museum Novitates. Number 3240, 27pp. 27 August 1998.
* Norell, M.A., Gaffney, E.S., and Dingus, L. (1995). *Discovering Dinosaurs in the American Museum of Natural History*. Alfred A. Knopf, Inc.:New York, 204 p.
* *Microvenator* in the Dinosaur Encyclopaedia

1. ↑ Ostrom, John H. (1970). "Stratigraphy and paleontology of the Cloverly Formation (Lower Cretaceous) of the Bighorn Basin area, Wyoming and Montana” Ibid. 35:234pp
2. ↑ Mackovicky, Peter J., Sues, Hans-Dieter. (1998). "Anatomy and phyolgenetic relationships of the Theropod Dinosaur *Microvenator celer* from the Lower Cretaceous of Montana” American Museum Novitates. Number 3240, 27pp. 27 August 1998.