''Microvenator'' (meaning "small hunter") is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...

from the Early Cretaceous

Cloverly Formation The Cloverly Formation is a geological formation of Early and Late Cretaceous age (Valanginian to Cenomanian stage) that is present in parts of Montana, Wyoming, Colorado and Utah in the western United States. It was named for a post office on th ...

in what is now south central

Montana Montana () is a state in the Mountain West division of the Western United States. It is bordered by Idaho to the west, North Dakota and South Dakota to the east, Wyoming to the south, and the Canadian provinces of Alberta, British Columb ...

. ''Microvenator'' was an

oviraptorosauria Oviraptorosaurs ("egg thief lizards") are a group of feathered maniraptoran dinosaurs from the Cretaceous Period of what are now Asia and North America. They are distinct for their characteristically short, beaked, parrot-like skulls, with or wi ...

theropod Theropoda (; ), whose members are known as theropods, is a dinosaur clade that is characterized by hollow bones and three toes and claws on each limb. Theropods are generally classed as a group of saurischian dinosaurs. They were ancestrally c ...

. The

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of sever ...

fossil is an incomplete skeleton, most likely a juvenile with a length of , and consequently, the adult size remains uncertain. ''Microvenator celer'' is primitive and may be the "sister taxon to all other oviraptorosaurs."Varricchio, D. J. 2001. Late Cretaceous oviraptorosaur (Theropoda) dinosaurs from Montana. pp. 42–57 in D. H. Tanke and K. Carpenter (eds.), Mesozoic Vertebrate Life. Indiana University Press, Indianapolis, Indiana.

Discovery

Barnum Brown collected the

type specimen In biology, a type is a particular specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally attached. In other words, a type is an example that serves to anchor or centralizes th ...

(AMNH 3041) in 1933 by a field party working for the American Museum of Natural History and he erroneously included ''

Deinonychus ''Deinonychus'' ( ; ) is a genus of dromaeosaurid theropod dinosaur with one described species, ''Deinonychus antirrhopus''. This species, which could grow up to long, lived during the early Cretaceous Period, about 115–108 million y ...

'' teeth with the specimen. Because of this, Brown informally dubbed it "Megadontosaurus" ("big-toothed lizard"), Brown made illustrations of it, but never published the name, a fate shared with several other

dinosaurs (''

'', '' Sauropelta'' and ''

Tenontosaurus ''Tenontosaurus'' ( ; ) is a genus of medium- to large-sized ornithopod dinosaur. It was a relatively medium sized ornithopod, reaching in length and in body mass. It had an unusually long, broad tail, which like its back was stiffened with a n ...

''). AMNH 3041 consists of a partial posterior skull, right dentary, 23 vertebrae, four ribs, the left coracoid, a partial left forelimb, a partial pelvis, and partial hindlimbs. It was not until 1970 that

John Ostrom John Harold Ostrom (February 18, 1928 – July 16, 2005) was an American paleontologist who revolutionized modern understanding of dinosaurs in the 1960s. As first proposed by Thomas Henry Huxley in the 1860s, Ostrom showed that dinosaurs were ...

described the type specimen as part of his work on the Cloverly Formation, naming it ''Microvenator celer'' meaning "swift small hunter" due to its long legs. Ostrom originally theorized it was part of

Othniel Marsh Othniel Charles Marsh (October 29, 1831 – March 18, 1899) was an American professor of Paleontology in Yale College and President of the National Academy of Sciences. He was one of the preeminent scientists in the field of paleontology. Among h ...

's Coeluridae due to features in the cervical vertebrae. Ostrom also referred a single tooth from the

Yale Peabody Museum The Peabody Museum of Natural History at Yale University is among the oldest, largest, and most prolific university natural history museums in the world. It was founded by the philanthropist George Peabody in 1866 at the behest of his nephew Ot ...

collection, YPM 5366, to this new species that likely belongs to ''

''.OSTROM, JOHN H. ''Stratigraphy and Paleontology of the Cloverly Formation (Lower Cretaceous) of the Bighorn Basin Area, Wyoming and Montana''. Yale University Press, 2020, https://doi.org/10.2307/j.ctvxkn7tk. The illustrations that Brown had prepared were finally published in a detailed and exhaustive monograph by Mackovicky and Sues in 1998. They confirmed that ''Microvenator'' is an

n, 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 ''

, Sauropelta,'' and ''

Acrocanthosaurus ''Acrocanthosaurus'' ( ; ) is a genus of carcharodontosaurid dinosaur that existed in what is now North America during the Aptian and early Albian stages of the Early Cretaceous, from 113 to 110 million years ago. Like most dinosaur genera, ' ...

'' in the Himes Member of the Cloverly Formation.

References

Caenagnathids Early Cretaceous dinosaurs of North America Taxa named by John Ostrom Fossil taxa described in 1970 Cloverly fauna Paleontology in Montana {{Theropod-stub

Discovery

Paleoenvironment

See also

References