Stagonolepis

Name: Stagonolepis ‭(‬Ornamented scale‭)‬.
Phonetic: Stag-on-oh-lep-is.
Named By: Louis Agassiz‭ ‬-‭ ‬1844.
Synonyms: Aetosauroides‭? ‬Calyptosuchus‭?
Classification: Chordata,‭ ‬Reptilia,‭ ‬Aetosauria,‭ ‬Stagonolepididae.
Species: S.‭ ‬robertsoni‭ (‬type‭)‬,‭ ‬S.‭ ‬olenkae,‭ ‬S.‭ ‬wellesi‭?
Diet: Herbivore.
Size: Up to about‭ ‬3‭ ‬meters long.
Known locations: Europe,‭ ‬Scotland‭ ‬-‭ ‬Lossiemouth Sandstone Formation and Poland‭ ‬-‭ ‬Drawno Beds Formation.‭ ‬Possibly North America and even South America.
Time period: Carnian of the Triassic.
Fossil representation: Multiple individuals.

       Stagonolepis had the typical aetosaur body form,‭ ‬quadrupedal,‭ ‬short legs and osteoderms than ran down the length of the body.‭ ‬This form could be described as crocodile-like,‭ ‬but caution should be exercised before assuming that Stagonolepis lived like a crocodile as well.‭ ‬Stagonolepis had neither piercing or slicing teeth,‭ ‬but peg-like teeth adapted for stripping the foliage from ferns.‭ ‬Stagonolepis also had a toothless beaked tip to the front of the jaws which could have been used for digging up buried plants.‭ ‬As such the osteoderm armour of Stagonolepis was probably more for protection from the jaws of archosaurian predators of the time possibly similar to Smok‭ (‬though this particular genus lived slightly later‭)‬.
       There is still some confusion about Stagonolepis,‭ ‬specifically regarding if any other genera are synonymous to it.‭ ‬Calyptosuchus from North America has for some time been considered to be a synonym to Stagonolepis,‭ ‬something which led to the creation of the species S.‭ ‬wellesi.‭ ‬Aetosauroides from South America has also been considered to be a synonym to Stagonolepis with smaller individuals belonging to S.‭ ‬robertsoni,‭ ‬larger ones to S.‭ ‬wellesi.‭ ‬Later studies of these fossils have now yielded the opinion that both Calyptosuchus and Aetosauroides are actually valid as distinct genera.‭ ‬If this is correct,‭ ‬then the species of Stagonolepis will be reduced to just two,‭ ‬S.‭ ‬robertsoni from Scotland and S.‭ ‬olenkae from Poland.‭ ‬Needless to say this will also mean that Stagonolepis only has a European distribution.

Further reading
-‭ ‬South American occurrences of the Adamanian‭ (‬Late Triassic:‭ ‬latest Carnian‭) ‬index taxon Stagonolepis‭ (‬Archosauria:‭ ‬Aetosauria‭) ‬and their biochronological significance,‭ ‬A.‭ ‬B.‭ ‬Heckert‭ ‬-‭ ‬2002.

-‭ ‬Aetosaur dermal armor from the Late Triassic of southwestern North America,‭ ‬with special reference to material from the Chinle Formation of Petrified Forest National Park,‭ ‬R.‭ ‬A.‭ ‬Long and K.‭ ‬L.‭ ‬Ballew.‭ ‬1985.

-‭ ‬The skull of an early Late Triassic aetosaur and the evolution of the stagonolepidid archosaurian reptiles,‭ ‬Tomasz Sulej‭ ‬-‭ ‬2010.

-‭ ‬A reappraisal of the taxonomic status of Aetosauroides‭ (‬Archosauria,‭ ‬Aetosauria‭) ‬specimens from the Late Triassic of South America and their proposed synonymy with Stagonolepis,‭ ‬J.‭ ‬B.‭ ‬Desojo‭ & ‬Martin D.‭ ‬Ezcurra‭ ‬-‭ ‬2011.



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