| Kenyasaurus | |
|---|---|
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Clade: | Neodiapsida |
| Genus: | †Kenyasaurus Harris &Carroll,1977 |
| Type species | |
| †Kenyasaurus mariakaniensis | |
Kenyasaurus is anextinctgenus ofbasaltangasaurid known from theEarly Triassicperiod ofCoast Province, southeasternKenya. It contains a single species,Kenyasaurus mariakaniensis.[1]
Kenyasaurus is known only from theholotype specimen,KNM-MA1, a well preserved and partially completepostcranialskeleton, lacking much of theneck,pectoral girdle andforelimb, which is hosted at theKenya National Museum. It was found at theMariakani locality which is located 25miles fromMombasa, southeasternKenya. It was collected from the upper part of theMaji ya Chumvi Beds (Maji-Ya-Chumvi Formation). These beds form the lower part of the Middle Duruma Sandstone Series (Duruma Group) and on the basis of lithological similarities with beds in Tanzania and Madagascar were dated to theInduan andOlenekian stages of theEarly Triassic period, about 251.0-245 million years ago.[1] This specimen represents the only reptilian fossils currently known from these beds.[2]
Kenyasaurus is a relatively small, lightly built, general lizard-like form. InKenyasaurus original description, Harris and Carroll (1977) assigned it to the "Eosuchia" (a defunct clade that used to unit all diapsids more advanced thanAraeoscelis) on the basis of its well developedsternum and that the fifth distaltarsal is not a separate element, but the fifthmetatarsal is not hooked. It was considered to be most closely related to theaquatic eosuchiansTangasaurus andHovasaurus (fromTanzania andMadagascar) based on its small size and general body proportions. Harris and Carroll noted that its tail is not specialized as a swimming organ as it is intangasaurids.[1]
Philip J. Currie (1982) redescribedTangasaurus and its relationships with other "eosuchians". He diagnosedKenyasaurus on the basis of fiveautapomorphies: It possesses low but anteroposteriorly elongateneural spines in the dorsal region, 56caudal vertebrae and 28 pairs ofcaudal ribs and transverse processes. Itsastragalus is almost triangular rather than primitive L-shape and it has pronounced process on fifth metatarsal for insertion of peroneus brevis.[2] Currie (1982) united two subfamilies within the Tangasauridae: Kenyasaurinae (that he named to includeKenyasaurus andThadeosaurus, both are thought to be terrestrial) and Tangasaurinae (to include the aquaticTangasaurus andHovasaurus). He allied Tangasauridae andYoungina together within superfamily Younginoidea which he named. Currie (1980) namedAcerosodontosaurus, and allied it with Younginoidea in the cladeYounginiformes.[2] Currie's (1982) classification of the Younginiformes had been accepted by many scientists[3] before they could perform large and computerized analyses.
More recent works that usephylogenetic analyses usually suggest that neither Younginoidea nor Younginiformes aremonophyletic.[4][5] Constanze Bickelmann, Johannes Müller andRobert R. Reisz (2009) redescribedAcerosodontosaurus and suggested an aquatic lifestyle for it. Their analysis is figured below, and it found support for two distinct families within "Younginiformes": the aquatic Tangasauridae, and the terrestrial Younginidae (in partialpolytomy with Tangasauridae). However, they found no support for the inclusion ofKenyasaurus within any of those families.[4] More resolved results were obtained by Reiszet al. (2011) in their description ofOrovenator. However, those results required the exclusion of the fragmentary taxaGalesphyrus,Kenyasaurus,Palaeagama andSaurosternon from their analysis.[5]
Kenyasaurus was first described and named byJohn M. Harris andRobert L. Carroll in1977 and thetype species isKenyasaurus mariakaniensis. Thegeneric name is derived from the name of theKenya in which the only known specimen was found, andGreeksauros, meaning "lizard". Thespecific name is derived from the name of the type locality of the genus,Mariakani.[1]
| |||||||||||||||||||||||
| |||||||||||||||||||||||
| |||||||||||||||||||||||
