Gypsonictops is an extinct genus of leptictidan mammals of the family Gypsonictopidae, which was described in 1927 by George Gaylord Simpson. Species in this genus were small mammals and the first representatives of the order Leptictida, that appeared during the Upper Cretaceous.
The genus is thought to have gone extinct before the Cenozoic began, but there are indications that it may have survived into the early Paleocene. Fossils have been found in the United States, Belgium, and Uzbekistan.
Like Cimolestes or Daulestes, it is possible that they had some distant relationship with the ungulates. It is one of the few eutherians that existed in North America during the Campanian, a period in which the multituberculates and the metatherians were the dominant ones on the continent.
Physiology[]
Like other prehistoric mammals of the Upper Cretaceous in North America, Gypsonictops had a particular dentition, with five premolars double-rooted in the lower jaw, while the vast majority of mammals only had four. On the other hand, the five premolars also were a very typical feature of the most primitive eutherians.
In the same way as the species of the genus Leptictidium, the P4 premolar was highly molarized, which caused confusion when analyzing a specimen of G. petersoni between P4 and molar M1. Eventually, P4 was found to be a paraconid-free premolar.
It is known that the Gypsonictops were eutherians and that they could be placentals, as they show very typical characteristics of these animals, although they belong to the Leptictida group, which includes some of the few non-placental eutherians that existed. Furthermore, the line between placental and non-placental eutherians is very thin, so the classification of Gypsonictops with precision is a very complicated task.
Taxonomy[]
The genus Gypsonictops was first classified within the family Leptictidae, by Simpson, along with all Leptictida of North America. This classification was maintained until 1967, year in which Leigh Van Valen created the family Gypsonictopidae for this genus especially. In 1997, Malcolm C. McKenna and Susan K. Bell suggested the possibility that this family contained up to seven different genera, but documents published since then have shown a high degree of skepticism about the proposal.
In popular culture[]
- A Gypsonictops appears in the opening of the first episode of Walking with Beasts using the same model as Leptictidium.