binomial Sinovenator changii. The generic name was derived from the Latin word Sinae, for China, and Venator, or "hunter". Meemann Chang is honoured by the species name for her contributions to the study of the Jehol Fauna.[1] As Chang is a female researcher, the epithet should have been "changae"; however, such mistakes cannot be emended according to the rules of the ICZN and therefore forms such as "Sinovenator changae" or "Sinovenator changiae" that sometimes appear in the literature, are incorrect.[citation needed
]
The
type specimen or holotype of Sinovenator changii is IVPP 12615, a partial skull and disarticulated skeleton. An additional specimen was by the original publication scientifically described and assigned as the paratype of the species: an incomplete but articulated postcranial skeleton, numbered IVPP 12583.[1] A third specimen was referred: IVPP V14322, a fragmentary skeleton. All three are in the collection of the IVPP in Beijing, China. However, Sinovenator fossils appear to be common in the Lujiatun Beds. In a 2006 survey of the Jehol Biota, Xu and Norell reported that hundreds of undescribed specimens are known.[2]
The fossils have been preserved three-dimensionally, not strongly compressed on a slab.
In 2014, the wrist of one specimen was described, IVPP V14009, an adult.[3] In 2018, PMOL-AD00102, consisting of a partial skull and mandibles, and six cervical vertebrae, was referred to the taxon.[4]
Description
Life restoration of sprinting Sinovenator.Size of Sinovenator compared to a human
Sinovenator is a
hands, and some of the highest non-avianencephalization quotients, meaning they were behaviourally advanced and had keen senses.[5] The holotype individual of Sinovenator was about the size of a chicken, less than a metre long.[6] In 2010, Gregory S. Paul estimated the weight of a one metre long individual at 2.5 kilogrammes.[7] However, the holotype and paratype are subadults; specimens are known with about twice their length. This makes it one of the larger species of troodontids in the ecosystem of the Yixian Formation
, the formation where it was found.
In the original description some distinguishing traits or
autapomorphies were established. The front edge of the antorbital fenestra, the large skull opening in front of the eye socket, is straight and vertically oriented. The frontal bone shows a vertical ridge touching the lacrimal bone. The surangular in the lower jaw has a T-shaped cross-section. The shinbone has a vertical ridge on the upper outer side, the crista cnemialis, touching a lower vertical ridge, the crista fibularis.[6]
There is a number of other notable traits. The upper branch of the praemaxilla excludes the maxilla from the nostril. The premaxillary teeth lack denticles; those on the maxillary teeth are small. The maxillary tooth row is positioned at some distance from the jaw rim. A fenestra promaxillaris is present. The branch of the jugal towards the postorbital is long, slender and inclined to the rear. The
occipital condyle. The braincase lacks a recessus suboticus and a crista otosphenoidalis. The rear of the pterygoid has a secondary, rod-like, process. The front dentary teeth are closely packed. The rear of the surangular is extraordinarily deep.[6]
Five sacrals are present, those of the middle being clearly larger. The
metatarsus, conforming to the subarctometatarsal condition.[6]
Phylogeny
Specimen IVPP V14322Details of specimen BMNHC Ph798, the skull is partially covered by fibula and tibia.
Bullatosauria, an earlier presumed close relationship between troodontids and ornithomimosaurs.[citation needed
]
Originally, the basal position of Sinovenator seemed to be corroborated by a very high age, the fossils being assumed to date from the Hauterivian. Later research however, indicated that the layers were younger.[citation needed]
In 2017, a study by Shen et al., describing the genus
synapomorphy uniting this group. The study recovered the following cladogram:[8]
.png)
