Longicrusavis

Longicrusavis Temporal range: Early Cretaceous, 122 Ma PreЄ Є O S D C P T J K Pg N ↓
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Dinosauria
Order:	Saurischia
Suborder:	Theropoda
Clade:	Ornithuromorpha
Family:	†Hongshanornithidae
Genus:	†Longicrusavis O'Connor et al., 2010
Species:	†L. houi O'Connor et al., 2010
Binomial name
Longicrusavis houi

Longicrusavis (meaning "long shin bird" in Latin) is an extinct genus of basal ornithuromorph bird within the family Hongshanornithidae. Remains have been found from the Lower Cretaceous Yixian Formation in Liaoning Province, China.

Description

Longicrusavis is known from the holotype specimen PKUP V1069, which consists of shale slab and counter slab. The skeleton is nearly complete and belongs to an adult individual, with carbonized feathers preserved around the head and forelimbs.

Like the closely related genus Hongshanornis, Longicrusavis has hindlimbs that are very long relative to the forelimbs. Longicrusavis has a rostrum that is more robust than that of Hongshanornis. The skull is roughly triangular in shape and the orbits, or eye sockets, are large. In lateral view, the dorsal margin of the skull is slightly concave, but not as much as the dorsal margin of the skull of Hongshanornis, where there is an abrupt constriction at the rostrum.

Although no teeth are preserved, they were likely present because there appears to be alveoli, or tooth sockets, in the premaxilla and maxilla. Hongshanornis also appears to have alveoli, despite being described as toothless when it was first named. No alveoli are found in the mandible, indicating that it was likely edentulous. Longicrusavis most likely lacked a beak because it does not possess groves and foramina that are indicative beaks in other taxa such as Archaeorhynchus.