{{Short description|Extinct genus of temnospondyls}} {{Automatic taxobox | fossil_range = [[Early Triassic]] | image = Eolydekkerina magna.jpg | image_upright = 1.1 | image_caption = Restoration of ''Eolydekkerina magna'' | taxon = Eolydekkerina | authority = Shishkin ''et al.'', [[1996 in paleontology|1996]] | type_species = {{extinct}}'''''Eolydekkerina magna''''' | type_species_authority = Shishkin ''et al.'', 1996 }}
'''''Eolydekkerina''''' is an extinct [[genus]] of [[temnospondyl]] from the [[Early Triassic]] of South Africa. It belongs to the family [[Lydekkerinidae]], along with the closely related genus ''[[Lydekkerina]]''. It is known from a single [[type species]], ''Eolydekkerina magna'', which was named in 1996 from a part of the [[Beaufort Group]] called the [[Lystrosaurus Assemblage Zone|''Lystrosaurus'' Assemblage Zone]].<ref name=SRK96>{{Cite journal | last1 = Shishkin | first1 = M. A. | last2 = Rubidge | first2 = B. S. | last3 = Kitching | first3 = J. W. | doi = 10.1098/rstb.1996.0147 | title = A New Lydekkerinid (Amphibia, Temnospondyli) from the Lower Triassic of South Africa: Implications for Evolution of the Early Capitosauroid Cranial Pattern | journal = Philosophical Transactions of the Royal Society B: Biological Sciences | volume = 351 | issue = 1347 | pages = 1635 | year = 1996 }}</ref>
==Description== ''Eolydekkerina'' is known from two specimens: a skull lacking the lower jaws and a poorly lower jaw, not associated with the skull. At {{convert|13|cm|in}} in length, the skull of ''Eolydekkerina'' is larger than that of any ''Lydekkerina'' specimen. The snout is proportionally much longer, and the eye sockets are placed farther apart than they are in ''Lydekkerina''. The proportions of the skull in ''Eolydekkerina'' are similar to those of the Australian lydekkerinid genus ''[[Chomatobatrachus]]''. However, ''Eolydekkerina'' shares more features in common with ''Lydekkerina'', including the nearly identical shape of bones at the back of the skull. The skull is roughly triangular in shape when viewed from above, with straight side margins. The margins of the eye socket are raised and the middle of the snout is slightly indented. Shallow grooves run along the surface of the skull behind the eye sockets and below the nostril openings.<ref name=SRK96/>
The lengthened skull of ''Eolydekkerina'', while different from that of ''Lydekkerina'', is similar to those of the related rhinesuchids and [[capitosauria]]ns. The short skull of ''Lydekkerina'' is thought to be a [[Synapomorphy|derived]] or advanced characteristic, suggesting that ''Lydekkerina'' evolved from a more typical longer-skulled temnospondyl. Since temnospondyl skulls tend to lengthen as individuals of a species age, the skull of ''Lydekkerina'' may represent a juvenile form, while the skull of ''Eolydekkerina'' represents a fully-grown adult form. If ''Lydekkerina'' is the descendant of ''Eolydekkerina'', it likely evolved by retaining juvenile characteristics into adulthood in a condition known as [[paedomorphosis]].<ref name=SRK96/>
==Paleoenvironment== Remains of ''Eolydekkerina'' were found in the lower part of the ''Lystrosaurus'' Assemblage Zone, a deposit that preserves very few amphibians. Amphibians become more numerous in younger parts of the ''Lystrosaurus'' Assemblage Zone with most specimens attributable to either ''Lydekkerina'' or to the [[dissorophoid]] ''[[Micropholis (amphibian)|Micropholis]]''. Several species of the family [[Rhytidosteidae]] have also been identified from the upper part of the ''Lystrosaurus'' Assemblage Zone. When fossils of ''Eolydekkerina'' were first found, they were thought to belong to a rhytidosteid, as a rhytidosteid called ''[[Pneumatostega]]'' had already been found in this part of the assemblage zone.
The lower ''Lystrosaurus'' Assemblage Zone is dominated by the [[synapsid]] ''[[Lystrosaurus]]'', as well as reptiles such as ''[[Owenetta]]'' and ''[[Proterosuchus]]''. Most small-bodied lydekkerinids such as ''Lydekkerina'' are found in this type of assemblage. Lydekkerinids of similar size to ''Eolydekkerina'' (such as ''Chomatobatrachus'') are usually found in amphibian-dominated assemblages where ''Lystrosaurus'' is not present. Therefore, the presence of ''Eolydekkerina'' in a reptile-dominated environment is unusual.<ref name=SRK96/>
==References== {{Reflist}}
{{Stereospondyli|S.}} {{Taxonbar|from=Q5381791}}
[[Category:Triassic temnospondyls of Africa]] [[Category:Early Triassic amphibians of Africa]]