| Ignavusaurus | |
|---|---|
 | |
| Restoration ofIgnavusaurus | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Clade: | Dinosauria |
| Clade: | Saurischia |
| Clade: | †Sauropodomorpha |
| Clade: | †Massopoda |
| Genus: | †Ignavusaurus Knoll,2010 |
| Species: | †I. rachelis |
| Binomial name | |
| †Ignavusaurus rachelis Knoll, 2010 | |
Ignavusaurus is agenus ofbasalsauropodomorphdinosaur that lived during theEarly Jurassic in what is nowLesotho. Its fossils were found in theUpper Elliot Formation which is probablyHettangian in age (around 200million years ago). It was described on thebasis of a partial, well preserved articulated skeleton. Thetype species,I. rachelis, was described in 2010 by Spanish palaeontologist F. Knoll.
Theholotype was discovered in southernLesotho nearHa Ralekoala. The fossils were discovered in a mostly articulated state, although the skull was badly damaged, having broken into more than 120 fragments. An unpublished 2002 Ph.D. dissertation referred to the remains, but they were not formally described for several years, and the find remained unpublished.[1]
In 2010, the fossils were described by F. Knoll of theMuseo Nacional de Ciencias Naturales-CSIC inMadrid as a new taxon,Ignavusaurus rachelis. The fossils were brought to theNational Museum of Natural History in Paris, where they were provisionally catalogued as BM HR 20; the plan was to return the fossils to Lesotho upon the opening of theLesotho National Museum.[1]
The generic nameIgnavusaurus is derived from theLatin wordignavus ("coward") andAncient Greeksauros ("lizard"). It refers to the type locality – Ha Ralekoala, that literally means "The place of the father of the coward". The specific name of thetype species,rachelis, honours Spanish palaeontologist Raquel López-Antoñanzas.[1]
The holotype had a body length of about 1.5 metres (4.9 ft) and weighed about 22.5 kilograms (50 lb).Histological analysis of thehumerus andfemur indicates that BM HR 20 was fast-growing individual, maybe less than one year old, based onage determination studies.[1]
Like other early sauropodomorphs,Ignavusaurus had a long, slender neck and tail. It generally resembledMassospondylus andMelanorosaurus, two other sauropodomorphs from southern Africa, although the shape and position of the teeth, among other factors, led Knoll to conclude that the remains belong to a previously unknown genus.[1]
Ignavusaurus is a basalsauropodomorph, a member of the long-necked,herbivorous,saurischian dinosaurs. Although originally recovered as more primitive thanPlateosauria by Knoll (2010), Yates et al. (2011) noted that some characters used to placeIgnavusaurus outside Massopoda are reflective of juvenile status and instead are more similar to juvenileMassospondylus, consideringIgnavusaurus probably synonymous withMassospondylus.[2] Meanwhile, acladistic analysis presented by Apaldetti et al. (2011) foundIgnavusaurus to be a valid genus which is most closely related toSarahsaurus withinMassopoda, somewhat agreeing with Yates et al. thatIgnavusaurus is not as primitive as originally thought.[3] A cladistic analysis conducted by Chapelle and Choiniere (2018) in their paper updating knowledge of the skull ofMassospondylus recoveredIgnavusaurus along withSarahsaurus in Massospondylidae, as did the cladistic analysis of Chapelle et al. (2019).[4][5]
