| Meroktenos | |
|---|---|
 | |
| Right femur | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Dinosauria |
| Clade: | Saurischia |
| Clade: | †Sauropodomorpha |
| Clade: | †Anchisauria |
| Genus: | †Meroktenos Peyre de Fabrègues & Allain, 2016 |
| Type species | |
| †Meroktenos thabanensis (Gauffre, 1993) | |
| Synonyms | |
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Meroktenos is a genus of basalsauropodomorphdinosaur that lived during theLate Triassic period of what is nowLesotho.
In 1959,François Ellenberger,Paul Ellenberger,Jean Fabre andLeonard Ginsburg discovered thetype specimen, a thighbone or femur and other assorted bones, south of the village of Thabana Morena. In 1962 these were addressed in a thesis by D. Costedoat.[1] The exact location the bones were recovered, is today unknown.[2]
In 1993,François-Xavier Gauffre assigned the remains to a second species ofMelanorosaurus:Melanorosaurus thabanensis. The description was provisional, and in 1997 the fossil was described in more detail in a publication byJacques van Heerden andPeter Malcolm Galton. Thespecific name refers to the site Thabana-Morena in Lesotho.[3]
Gauffre assumed that the specimen had been found in theUpper Elliot Formation dating from theHettangian-Sinemurian and thus was about twenty million year younger thanMelanorosaurus readi.[3] In 1996, he revised the date to theLower Elliot Formation of the late Triassic in his non-published dissertation. He also referred the thighbone to a new genus and speciesThotobolosaurus (nowKholumolumo[4]). This remained a non-validnomen ex dissertatione, as the name would never be published; furthermore the type material of this species does not coincide with that ofM. thabanensis.[5]
In 2016,M. thabanensis was appointed to the separate genusMeroktenos byClaire Peyre de Fabrègues andRonan Allain. The genus name is a combination of ancient Greek μηρός,meros ("thigh") and κτῆνος,ktènos ("beast").[2] Thecombinatio nova thus becomesMeroktenos thabanensis, thetype species is the originalMelanorosaurus thabanensis.
Theholotype,MNHN.F.LES 16, consists of a right thighbone (MNHN.F.LES16c), a portion of the right ilium, with a piece of a vertebralneural arch (MNHN.F.LES16a); a left pubic bone (MNHN.F.LES16b); and a second right metatarsal (MNHN.F.LES16d) associated with the skeleton. In 2016, a new specimen, MNHN.F.LES351, was referred to the species; consisting of a cervical vertebra, a left ulna and a, probably left, radius. It might have belonged to the same individual as the holotype, but this cannot be strictly proven.[2]
Meroktenos has a femur length of around forty-eight centimeters,[2] suggesting a body length of about four meters.
In 2016, a revised list of distinguishing traits was given. The blade height of the ilium, measured from the highest point of the antitrochanter to the upper edge of the blade is 60% of the total height of the ilium, including peduncles. The rear blade of the ilium is roughly triangular in side view. The femur is very compact with a robusticity index, length divided by the circumference of the shaft, of 2.09. The femur has a straight shaft in both side and front views. The femoral shaft is substantially wider transversely than it is wide in side view, with a ratio of 1.58. On the rear of the femoral shaft, the fourth trochanter is oriented obliquely, running from the upper and inner side to the lower and outer side.[2]
In 2016,Meroktenos was placed in theSauropodomorpha, in a basal position. According to acladistic analysis,Meroktenos formed a polytomy withBlikanasaurus and more derived taxa, aboveAardonyx in the evolutionary tree and below a polytomy includingCamelotia,Melanorosaurus and more derived groups:[2]
A 2021 study by Pol and colleagues foundMeroktenos to be a member ofLessemsauridae, being the sister taxon of a clade formed byKholumolumo andLedumahadi:[6]
| Sauropodiformes |
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The relative transverse width of the femur, the eccentricity, is remarkably high for such a small animal. These proportions were known previously only fromSauropoda and explained as an adaptation to a very high absolute weight. Because the holotype probably was not a young animal and is unlikely to have attained giant proportions, the trait must have had a different function.[2]
