''Deltaherpeton'' is an

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of colosteid from middle

Mississippian Mississippian may refer to: * Mississippian (geology), a subperiod of the Carboniferous period in the geologic timescale, roughly 360 to 325 million years ago * Mississippian cultures, a network of precontact cultures across the midwest and Easte ...

(late

Viséan The Visean, Viséan or Visian is an age in the ICS geologic timescale or a stage in the stratigraphic column. It is the second stage of the Mississippian, the lower subsystem of the Carboniferous. The Visean lasted from to Ma. It follows ...

age) deposits of

Delta Delta commonly refers to: * Delta (letter) (Δ or δ), the fourth letter of the Greek alphabet * D (NATO phonetic alphabet: "Delta"), the fourth letter in the Latin alphabet * River delta, at a river mouth * Delta Air Lines, a major US carrier ...

Iowa Iowa ( ) is a U.S. state, state in the upper Midwestern United States, Midwestern region of the United States. It borders the Mississippi River to the east and the Missouri River and Big Sioux River to the west; Wisconsin to the northeast, Ill ...

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

. It was first named by John R. Bolt and R. Eric Lombard in

2010 The year saw a multitude of natural and environmental disasters such as the 2010 Haiti earthquake, the Deepwater Horizon oil spill, and the 2010 Chile earthquake. The 2009 swine flu pandemic, swine flu pandemic which began the previous year ...

and the type species is ''Deltaherpeton hiemstrae''. ''Deltaherpeton'' can be differentiated from other colosteids due to possessing several unique bones along the midline of the skull, separating paired skull bones which typically contact each other along the midline. These include an internasal, an oval-shaped bone which lies at the intersection of the paired

premaxilla The premaxilla (or praemaxilla) is one of a pair of small cranial bones at the very tip of the upper jaw of many animals, usually, but not always, bearing teeth. In humans, they are fused with the maxilla. The "premaxilla" of therian mammals h ...

e and

nasal Nasal is an adjective referring to the nose, part of human or animal anatomy. It may also be shorthand for the following uses in combination: * With reference to the human nose: ** Nasal administration, a method of pharmaceutical drug delivery * ...

bones at the top of the snout. Internasals are known from several of the earliest four-limbed vertebrates, such as ''

Acanthostega ''Acanthostega'', from Ancient Greek ἄκανθα (''ákantha''), meaning "spine", and στέγη (''stégē''), meaning "roof", is an extinct genus of stem tetrapoda, stem-tetrapod, among the first vertebrates, vertebrate animals to have recogn ...

'', ''

Ichthyostega ''Ichthyostega'', from Ancient Greek ἰχθύς (''ikthús''), meaning "fish", and στέγη (''stégē''), meaning "roof", is an Extinction, extinct genus of limbed tetrapodomorpha, tetrapodomorphs from the Devonian, Late Devonian of what is ...

'', and baphetids. Further back, what seems to be a pair of

lozenge Lozenge or losange may refer to: * Lozenge (shape), a type of rhombus *Throat lozenge A throat lozenge (also known as a cough drop, sore throat sweet, troche, cachou, pastille or cough sweet) is a small, typically medicated tablet intended to ...

-shape bones lie at the intersection of the nasal bones and frontal bones. These bones may be interfrontonasals, which have been found in some eryopoids and microsaurs. In addition, ''Deltaherpeton'' has a single

postparietal Postparietals are cranial bones present in fish and many Tetrapod, tetrapods. Although initially a pair of bones, many lineages possess postparietals which were fused into a single bone. The postparietals were Dermal bone, dermal bones situated alo ...

(rather than a pair), which separates the left and right

supratemporal The supratemporal bone is a paired Skull, cranial bone present in many Tetrapod, tetrapods and Tetrapodomorpha, tetrapodomorph fish. It is part of the temporal region (the portion of the skull roof behind the eyes), usually lying medial (inwards) re ...

and tabular bones at the rear edge of the skull. Lone postparietals are rare among non-amniote tetrapods and tetrapod relatives; only ''Ichthyostega'' and

diadectomorphs Diadectomorpha is a clade of large tetrapods that lived in Euramerica during the Carboniferous and Early Permian periods and in Asia during Late Permian (Wuchiapingian), They have typically been classified as advanced reptiliomorphs (transitional ...

are known to possess them. The discovery of ''Deltaherpeton'' prompted a review and re-augmentation of the defining characteristics for the family

Colosteidae Colosteidae is a Family (biology), family of stegocephalians (stem-group tetrapod, tetrapods) that lived in the Carboniferous period. They possessed a variety of characteristics from different tetrapod or stem-tetrapod groups, which made them his ...

, though it did not help to clarify the relationship between colosteids and other early

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. Though it is believed that ''Deltaherpeton'' is more derived, the species is thought to have shared its environment with other early four-limbed vertebrates such as '' Whatcheeria'', approximately 339.4 to 336 million years ago.

References

{{Taxonbar, from=Q3705236 Colosteidae Mississippian sarcopterygians of North America Fossil taxa described in 2010