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The fossil record of temnospondyl amphibians in the immediate wake of the Permo-Triassic mass extinction captures extensive taxic and ecological diversity, with most records known from high paleolatitudinal settings. In southern Pangea, the most substantial records come from South Africa and Australia, with a total of over 20 taxa presently recognized. Temnospondyls have also been known from correlated horizons in the lower Fremouw Formation of Antarctica since the late 1960s, but these records are mostly fragmentary, thereby limiting taxonomic resolution to the family level and subsequent biostratigraphic correlations and comparisons between high-latitude basins. Here we report substantial new material of the amphibamiform Micropholis stowi, a relic dissorophoid previously known only from the Katberg Formation (Lystrosaurus declivis Assemblage Zone) of South Africa, from the lower Fremouw Formation. The exceptional preservation of the recently recovered material permits not only confident taxonomic referral but also tentative association of several individuals to the broad-headed morph of the taxon. The recognition of M. stowi in Antarctica represents only the fourth geographic occurrence of a dissorophoid from southern Pangea and supports the hypothesis that high-latitude environments served as refugia for temnospondyls during the mass extinction. In the case of M. stowi, such refugia permitted the persistence of a predominantly Permo-Carboniferous clade, and the Antarctic records discussed here further hint at a poorly sampled cryptic distribution, both of amphibamiforms in southern Pangea and of small-bodied temnospondyls in early Mesozoic deposits.
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This content will become publicly available on May 3, 2026
Watch your step: caution in bridging the trackway—trackmaker divide in Carboniferous tetrapods
The field of ichnology has been a branch of paleontology since the mid 19th century. Vertebrate tracks are a vast dataset compared to vertebrate body fossils: an individual organism will leave only one body, but will leave many tracks and only one body to potentially be preserved. Tracks are direct records of organismal behavior and can be used as proxies for biodiversity and paleoecology. The use of anatomy-consistent morphology in ichnotaxonomy incorporates trackmaker identity by correlating the morphology of the track with that of available track-maker(s). Standard practice is to interpret ichnotaxa to a family level for trackmakers, but the Linnaean rank and cladistic status of trackmaker taxa actually varies greatly. Our work aims to harmonize the ichnological and body fossil records of early Carboniferous tetrapods to better ground trackmaker inferences. For example, the Pennsylvanian-Permian ichnogenus Limnopus is referred to eryopid temnospondyls. However, large ichnospecies (e.g., L. littoralis, L. waynesburgensis) are 200% larger than small ichnospecies (e.g., L. vagus). It has been suggested that the different ichnospecies of Limnopus represent distinct ontogenetic stages of the trackmaker, including the similar but smaller ichnogenus Batrachichnus. Of the few Carboniferous temnospondyls for which the manus and pes are both known in detail, the morphology of the large Limnopus morph is consistent with that of Eryops, but edopid trackmakers cannot be discounted. This has minimal implications for reconstructing ecosystems, given the similarities between eryopids and edopids. However, this uncertainty in the identity of the trackmaker makes the use of Limnopus as a biostratigraphic appearance datum for Eryopidae problematic. The recent consolidation of Limnopus species into the type (L. heterodactylopus) ensures greater ichnotaxonomic consistency, but weakens the track-trackmaker link. Interpretation of Carboniferous pentadactyl tracks must account for the presence of pentadactyly among multiple stem tetrapod families by the late Mississippian. Trackways and skeletal remains — specifically autopodia — are scant in the earlier Mississippian, but both hint at a reduction of pedal digit number to five by this time. The timing of manual digit reduction remains uncertain, but coexistence of a probably hexadactyl manus (Pederpes, Whatcheeriidae) with pendatactyl and tetradactyl manual prints highlights the earliest Carboniferous as a time of diversity and dynamism in early tetrapod morphology.
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- Award ID(s):
- 2209043
- PAR ID:
- 10610638
- Editor(s):
- Murray, Alison M; Demers-Povtin, Alexandre V; Holmes, Robert B
- Publisher / Repository:
- Vertebrate Anatomy Morphology Palaeontology
- Date Published:
- Journal Name:
- Vertebrate Anatomy Morphology Palaeontology
- Volume:
- 13
- ISSN:
- 2292-1389
- Page Range / eLocation ID:
- 1 to 47
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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