Eodeinonychus

Life restoration

## Type species

†***E. venatrix***

***Eodeinonychus venatrix*** ("dawn *Deinonychus* huntress") is an extinct genus of Dromaeosaur Theropod dinosaur, closely related to, though older than, *Deinonychus.* *E. venatrix* was smaller than its cousin, at only 4 feet long. It lived in Colorado, Montana, Wyoming, and North and South Dakota, in the Morrison Formation. The genus went extinct 155 mya.

## Etymology

The name *Eodeinonychus* comes from the greek word *ēōs*, meaning "dawn", and the name *Deinonychus*, a similar dinosaur. The name *Deinonychus*, in turn, comes from the greek *deinós*, "terrible", and *ónux* or *ónuchos*, "claw". Thus, *Eodeinonychus* means "dawn terrible claw".

## Discovery

Remains of *Eodeinonychus* have been found in the Morrison Formation in several U.S states, most notably Colorado, Wyoming, and Montana. The first remains of *Eodeinonychus* were found in 2002 by American palaeontologist Herbert Doke. It was originally named "Robertosaurus" after U.S biologist Ian Roberto. In 2007, a new analysis was made on "Robertosaurus", and it was found that not all of the bones were actually from 1 animal. Thus, some of the bones were transferred to *Ornitholestes*, and the rest were given the new name *Eodeinonychus.*

## Description

As one of the most basal Dromaeosaurs, *E. venatrix* was a smallish member, capable of reaching lengths of 4 feet as an adult. It had the long sickle claw on the second toe of each hind foot, a common trait shared by all members of Dromaeosauridae. However, those of *E. venatrix* were slightly smaller and less robust than those on *Deinonychus*, *Utahraptor*, and *Dakotaraptor*. Like all other Dromaeosaurs, the sickle claws of *E. venatrix* where, in life, coated in a horny sheath. The eyes of *E. venatrix* where smaller than those of some other Dromaeosaurs, suggesting that this dinosaur was diurnal. It had a strong bite, meaning it could inflict deep wounds by biting down on any spot on prey they could reach. It is very likely that *E. venatrix* had feathers, with some scientists suggesting that it could fly. This is highly disputed, and most scientists say that *E. venatrix*'s arms weren't built in such a way to allow flight.

## Hunting

Like all Dromaeosaurs, *Eodeinonychus* was an obligate carnivore. It probably hunted small to medium-sized dinosaurs, as well as mammals, lizards, and birds. It chased down its prey and then slashed at it with its sickle claws. *Eodeinonychus* was probably one of the smartest Dromaeosaurs, and scientists have hypothesized that it may have understood that slashing at an animal's neck would be more effective at killing it than its belly, flanks, or limbs. Several specimens of *Eodeinonychus* have been found together, suggesting that the dinosaurs were hunting in a pack. However, palaeontologist Francois Bordeaux noted that, while *Eodeinonychus*' brain was quite large for a dinosaur of its size, it probably wasn't smart enough to coordinate in packs.

## Classification

Initially, *Eodeinonychus* was placed in Dromaeosaurinae, the same group as *Deinonychus*, *Dromaeosaurus*, and *Utahraptor*. However, palaeontologist CyclonicWrath765 did a study on *Eodeinonychus* and found that it was quite basal, more so than any member of Dromaeosaurinae. CW noted that *Eodeinonychus* was probably more closely related to *Adasaurus* and *Tianyuraptor* than to other Dromaeosaurs.