Whatcheeriidae is an extinct

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

stem-tetrapods The Stem Tetrapoda are a cladistically defined group, consisting of all animals more closely related to extant four-legged vertebrates than to their closest extant relatives (the lungfish), but excluding the crown group Tetrapoda. They are thus p ...

which lived in the Mississippian sub-period, a subdivision of the

Carboniferous The Carboniferous ( ) is a Geologic time scale, geologic period and System (stratigraphy), system of the Paleozoic era (geology), era that spans 60 million years, from the end of the Devonian Period Ma (million years ago) to the beginning of the ...

period. It contains the genera '' Pederpes'', '' Whatcheeria'', and possibly '' Ossinodus''. Fossils of a possible whatcheeriid have been found from the Red Hill locality of

Pennsylvania Pennsylvania, officially the Commonwealth of Pennsylvania, is a U.S. state, state spanning the Mid-Atlantic (United States), Mid-Atlantic, Northeastern United States, Northeastern, Appalachian, and Great Lakes region, Great Lakes regions o ...

. If these remains are from a whatcheeriid, they extend the range of the family into the

Late Devonian The Devonian ( ) is a geologic period and system of the Paleozoic era during the Phanerozoic eon, spanning 60.3 million years from the end of the preceding Silurian period at million years ago ( Ma), to the beginning of the succeeding ...

and suggest that advanced

tetrapod A tetrapod (; from Ancient Greek :wiktionary:τετρα-#Ancient Greek, τετρα- ''(tetra-)'' 'four' and :wiktionary:πούς#Ancient Greek, πούς ''(poús)'' 'foot') is any four-Limb (anatomy), limbed vertebrate animal of the clade Tetr ...

s may have lived alongside primitive tetrapod ancestors like ''

Hynerpeton ''Hynerpeton'' ( ) is an extinct genus of early four-limbed vertebrate that lived in the rivers and ponds of Pennsylvania during the Late Devonian period, around 365 to 363 million years ago. The only known species of ''Hynerpeton'' is ''H. basse ...

'' and '' Densignathus''. They also imply that a very long

ghost lineage A ghost lineage is a hypothesized ancestor in a species lineage that has left no fossil evidence, but can still be inferred to exist or have existed because of gaps in the fossil record or genomic evidence. The process of determining a ghost line ...

of whatcheeriids lived through

Romer's gap Romer's gap is an apparent gap in the Paleozoic tetrapod fossil record noted in the studies of paleontology and evolutionary biology, which represent periods in the Early Carboniferous from which excavators have not yet found relevant transition ...

, a period during the Early Carboniferous conspicuously lacking in tetrapod remains.

Classification

Currently, using modern

cladistic Cladistics ( ; from Ancient Greek 'branch') is an approach to biological classification in which organisms are categorized in groups ("clades") based on hypotheses of most recent common ancestry. The evidence for hypothesized relationships is ...

taxonomy, Whatcheeriidae is not placed in

Amphibia Amphibians are ectothermic, anamniotic, four-limbed vertebrate animals that constitute the class Amphibia. In its broadest sense, it is a paraphyletic group encompassing all tetrapods, but excluding the amniotes (tetrapods with an amniotic ...

or any other class but simply as its own family within stem-group tetrapods. The analysis below was conducted by Swartz in 2012, showing the relationship of whatcheeriids with other stem-tetrapods.

References

Taxonomicon article on Whatcheeriidae

Zipcode Zoo article on Whatcheeriidae
{{Taxonbar, from=Q150777 Stegocephali Tetrapodomorph families Mississippian first appearances Mississippian extinctions