Lesothosaurus
Name:
Lesothosaurus
(Lesotho lizard).
Phonetic: Leh-so-foe-sore-us.
Named By: Peter M. Galton - 1978.
Synonyms: Stormbergia?
Classification: Chordata, Reptilia, Dinosauria,
Ornithischia, Genasauria, Lesothosauridae.
Species: L. diagnosticus
(type).
Diet: Herbivore.
Size: About 1 meter long.
Known locations: South Africa - Upper Elliot
Formation.
Time period: Hettangian/Sinemurian of the Jurassic.
Fossil representation: Remains of several
individuals.
Although
only a very small dinosaur, Lesothosaurus has
raised a lot of
questions as to exactly what it was and how the genus was related to
other ornithischian dinosaurs. When first described by Galton in
1978, Lesothosaurus was proposed to be an
ornithopod. However the
genus has also been considered to be a very primitive member or the
ornithischia, a primitive neornithischian as well as a very primitive
thyreophoran (the group that stegosaurian
and ankylosaurian
dinosaurs
stem from).
Lesothosaurus
has also been considered to be a synonym to the genus Fabrosaurus
that was named earlier in 1964. However, since Fabrosaurus
was
based upon the description of a jawbone and three teeth, it has been
extremely hard to establish this with certainty. Another genus called
Stormbergia
that was named in 2005 has also been speculated to be
the fully grown form of Lesothosaurus. If true
then Stormbergia would
actually be a synonym to Lesothosaurus.
In
terms of being a living dinosaur, Lesothosaurus
had rear legs that
were very long in proportion to their body size, something that leads
to the assumption that Lesothosaurus relied upon
small size, speed
and agility to evade predators such as larger theropod dinosaurs of the
saurischian line. The fore limbs were short by comparison to the legs
and with small hands, however each hand possessed five fingers,
four of which were well developed.
In
life Lesothosaurus would have had a keratinous beak
formed on the
anterior of the upper and lower jaws, and this would have been of use
for snipping off plant parts. Within the mouth there were two kinds
of teeth, twelve fang-like one in the upper jaw, and leaf-shaped
shearing teeth behind them and in the lower jaw. It would be the
combination of the horny beak and the up/down shearing action of the
teeth which would have been the main food processing areas before food
was swallowed.
Further reading
- Fabrosauridae, the basal family of ornithischian dinosaurs
(Reptilia: Ornithischia) - Pal�ontologische Zeitschrift
52(1/2):138-159 - Peter M. Galton - 1978.
- The 'fabrosaurid' ornithischian dinosaurs of the Upper Elliot
Formation (Lower Jurassic) of South Africa and Lesotho -
Zoological Journal of the Linnean Society 145: 175-218 - R.
J. Butler - 2005.
- Ontogenetic change and adult body size of the early ornithischian
dinosaur Lesothosaurus diagnosticus: implications
for basal
ornithischian taxonomy - Gondwana Research. online 17 (1):
171 - F. Knoll, K. Padian & A. de Ricqles -
2009.
- Postcranial anatomy of Lesothosaurus diagnosticus
(Dinosauria:
Ornithischia) from the Lower Jurassic of southern Africa: implications
for basal ornithischian taxonomy and systematics. - Zoological Journal
of the Linnean Society. - Matthew G. Baron, David B. Norman &
Paul M. Barrett - 2016.
- Digital reconstruction of the mandible of an adult Lesothosaurus
diagnosticus with insight into the tooth replacement process
and diet.
- PeerJ, 5: e3054. - L. Sciscio, F. Knoll, E. M. Bordy, M. O. de Kock
& R. Redelstorff - 2017.
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