Luskhan
| Luskhan Temporal range: Hauterivian | |
|---|---|
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Superorder: | †Sauropterygia |
| Order: | †Plesiosauria |
| Family: | †Pliosauridae |
| Subfamily: | †Brachaucheninae |
| Genus: | †Luskhan Fischer et al. 2017 |
| Species: | †L. itilensis |
| Binomial name | |
| Luskhan itilensis Fischer et al., 2017 | |
Luskhan is an extinct genus of pliosaurs. The type and only species is Luskhan itilensis Fischer et al. 2017.[1]
Description
Luskhan itilensis is known from a nearly complete fossil skeleton found near the Volga River in western Russia. The skeleton measures 6.5 m (21 ft) long. At the end of its relatively short neck, the long skull tapers to an elongate snout, with a lower jaw 1.6 m (5.2 ft) long. The fossil dates to the Hauterivian age of the early Cretaceous Period, about 130 million years ago.[1]
A long list of characters set Luskhan apart from other pliosaurs, including
- seven premaxillary teeth, the first first of which is procumbent and nearly horizontal
- the space between the first and second premaxillary alveoli is wide and strongly swollen
- the suture between the squamosal and quadrate bones expands posteriorly into a hook-like rugose process on the squamosal[1]
Many of the Luskhan's features show its ancestors diverged early from other brachauchenine pliosaurs, around the beginning of the Cretaceous Period. Other features make Luskhan unusually specialized for its clade. The narrow rostrum resembles that of polycotylids such as Dolichorhynchops, which while also plesiosaurs were only distantly related, last sharing an ancestor with pliosaurs like Luskhan over 200 million years ago. That trait, along with a long mandibular symphysis, and smaller isodont teeth, implies a diet of softer prey such as fish and squid, rather than the large prey eaten by other thalassophoneans. While the resemblance to polycotylids extends to the skull and teeth, the axial skeleton and flippers remain more like other thalassophonean pliosaurs. Luskhan shows that pliosaurs continued to be more ecologically diverse in the Cretaceous than previously thought, and that pliosaurs that ate large prey evolved into diets of medium-sized prey several times in their history.[1]
Discovery and naming
The holotype, specimen YKM 68344/1_262, was found by Gleb N. Uspensky.
The name Luskhan comes from luus, a spirit and master of water in Mongolian and Turkic legend, and khan, meaning chief. Itil is the ancient Turkic name for the Volga River, hence the species epithet itilensis means "from the Volga".[1]
Classification
The following cladogram follows an analysis by Fischer et al., 2017.[1] For the most part this tree shows only genera, and is a reduced consensus tree.