Ianthodon

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Ianthodon
Temporal range: Pennsylvanian,
~304  Ma
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IanthodonReconstruction.png
I. schultzei cranial and skeletal reconstruction
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Synapsida
Clade: Eupelycosauria
Clade: Metopophora
Clade: Haptodontiformes
Genus: Ianthodon
Kissel & Reisz, 2004
Type species
Ianthodon schultzei
Kissel & Reisz, 2004
Holotype KUVP 133735 Ianthodon schultzei 35.jpg
Holotype KUVP 133735

Ianthodon is an extinct genus of basal haptodontiform synapsids from the Late Carboniferous about 304 million years ago. The taxon was discovered and named by Kissel & Reisz in 2004. [1] The only species in the taxon, Ianthodon schultzei, was found by separating it from a block that also contained the remains of Petrolacosaurus and Haptodus . The evolutionary significance of the taxon wasn't realized until a publication in 2015. [2] The fossil of this organism was discovered in Garnett, Kansas. [2]

Contents

Description

Ianthodon was first named by Kissel & Reisz in 2004, [1] and a more detailed specimen was reevaluated in 2014. [2] This single juvenile skeleton with delicate bones has an estimated skull length of around 10 cm, which is similar to other taxa, such as Haptodus, [3] during the same development stage. [1] [4] The specimen was easily distinguished from the skeletal element of Petrolacosaurus [5] by the position and the proportion of foreman and supinator process in the humeri.

Skull

It can be distinguished from Haptodus [6] [3] by its narrower skull and dentition. The higher number of precaninie maxillary teeth and the more rectangular shape of the humerus distinguish the holotype of H. garnettensis [5] from that of Ianthodon. The teeth of Ianthodon have wide bases but slender crowns, unusual among contemporary amniotes and indicating that Ianthodon occupied a different trophic niche from the bulbous-crowned Haptodus to which it was closely related. [6] Like other sphenacodonts, Ianthodon has a tall lacrimal bone, and so would have had a proportionally taller snout than more basal synapsids such as varanopids and eothyridids. [7] [2]

Classification

Ianthodon belongs to the clade Sphenacodontia within the clade Sphenacomorpha. Ianthodon has been considered the basalmost known sphenacodont. [2] The cladogram below follows a cladistic analysis by Spindler and colleagues, 2014. [2]

See also

Related Research Articles

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Edaphosauridae is a family of mostly large Late Carboniferous to Early Permian synapsids. Edaphosaur fossils are so far known only from North America and Europe.

<span class="mw-page-title-main">Sphenacodontia</span> Clade of synapsids

Sphenacodontia is a stem-based clade of derived synapsids. It was defined by Amson and Laurin (2011) as "the largest clade that includes Haptodus baylei, Haptodus garnettensis and Sphenacodon ferox, but not Edaphosaurus pogonias". They first appear during the Late Pennsylvanian epoch. From the end of the Carboniferous to the end of the Permian, most of them remained large, with only some secondarily becoming small in size.

<span class="mw-page-title-main">Eupelycosauria</span> Clade of synapsids

Eupelycosauria is a large clade of animals characterized by the unique shape of their skull, encompassing all mammals and their closest extinct relatives. They first appeared 308 million years ago during the Early Pennsylvanian epoch, with the fossils of Echinerpeton and perhaps an even earlier genus, Protoclepsydrops, representing just one of the many stages in the evolution of mammals, in contrast to their earlier amniote ancestors.

<i>Petrolacosaurus</i> Genus of tetrapods

Petrolacosaurus is an extinct genus of diapsid reptile from the late Carboniferous period. It was a small, 40-centimetre (16 in) long reptile, and one of the earliest known reptile with two temporal fenestrae. This means that it was at the base of Diapsida, the largest and most successful radiation of reptiles that would eventually include all modern reptile groups, as well as dinosaurs and other famous extinct reptiles such as plesiosaurs, ichthyosaurs, and pterosaurs. However, Petrolacosaurus itself was part of Araeoscelida, a short-lived early branch of the diapsid family tree which went extinct in the mid-Permian.

<span class="mw-page-title-main">Caseasauria</span> Extinct clade of synapsids

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Varanopidae is an extinct family of amniotes that resembled monitor lizards and may have filled a similar niche, hence the name. Typically, they are considered synapsids that evolved from an Archaeothyris-like synapsid in the Late Carboniferous. Although some studies from the late 2010s have recovered them being taxonomically closer to diapsid reptiles, recent studies from the early 2020s support their traditional placement as synapsids on the basis of high degree of bone labyrinth ossification, maxillary canal morphology and phylogenetic analyses. A varanopid from the latest Middle Permian Pristerognathus Assemblage Zone is the youngest known varanopid and the last member of the "pelycosaur" group of synapsids.

<span class="mw-page-title-main">Sphenacodontoidea</span> Superfamily of synapsids

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<i>Haptodus</i> Extinct genus of synapsids

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<i>Eothyris</i> Extinct genus of synapsids

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<i>Pantelosaurus</i> Extinct genus of synapsids

Pantelosaurus is an extinct genus of basal sphenacodonts known from the Early Permian period of Saxony, Germany. It contains a single species, Pantelosaurus saxonicus.

<i>Palaeohatteria</i> Extinct genus of synapsids

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"Haptodus" garnettensis is an extinct species of basal sphenacodont from the Late Carboniferous (Pennsylvanian) of Kansas, USA.

<i>Echinerpeton</i> Extinct genus of synapsids

Echinerpeton is an extinct genus of synapsid, including the single species Echinerpeton intermedium from the Late Carboniferous of Nova Scotia, Canada. The name means 'spiny lizard' (Greek). Along with its contemporary Archaeothyris, Echinerpeton is the oldest known synapsid, having lived around 308 million years ago. It is known from six small, fragmentary fossils, which were found in an outcrop of the Morien Group near the town of Florence. The most complete specimen preserves articulated vertebrae with high neural spines, indicating that Echinerpeton was a sail-backed synapsid like the better known Dimetrodon, Sphenacodon, and Edaphosaurus. However, the relationship of Echinerpeton to these other forms is unclear, and its phylogenetic placement among basal synapsids remains uncertain.

<i>Milosaurus</i> Extinct genus of synapsids

Milosaurus is an extinct genus of non-mammalian synapsids native to Illinois that was alive during the latest Carboniferous and earliest Permian. It was named in 1970 on the basis of FMNH 701, a partial skeleton, as well as referred material.

<i>Xyrospondylus</i> Extinct genus of synapsids

Xyrospondylus is an extinct genus of non-mammalian synapsids belonging to the Edaphosauridae. The type species, X. ecordi, was named in 1982; it was originally named as a species of Edaphosaurus in 1957.

<i>Acleistorhinus</i> Extinct genus of reptiles

Acleistorhinus (ah-kles-toe-RYE-nuss) is an extinct genus of parareptile known from the Early Permian of Oklahoma. It is notable for being the earliest known anapsid reptile yet discovered. The morphology of the lower temporal fenestra of the skull of Acleistorhinus bears a superficial resemblance to that seen in early synapsids, a result of convergent evolution. Only a single species, A. pteroticus, is known, and it is classified in the Family Acleistorhinidae, along with Colobomycter.

<i>Kenomagnathus</i> Extinct genus of synapsids

Kenomagnathus is a genus of synapsid belonging to the Sphenacodontia, which lived during the Pennsylvanian subperiod of the Carboniferous in what is now Garnett, Kansas, United States. It contains one species, Kenomagnathus scottae, based on a specimen consisting of the maxilla and lacrimal bones of the skull, which was catalogued as ROM 43608 and originally classified as belonging to "Haptodus" garnettensis. Frederik Spindler named it as a new genus in 2020.

References

  1. 1 2 3 Kissel, R. A. & Reisz, R. R. Synapsid fauna of the Upper Pennsylvanian Rock Lake Shale near Garnett, Kansas and the diversity pattern of early amniotes. In G. Arratia, M. V. H. Wilson & R. Cloutier (eds.). Recent Advances in the Origin and Early Radiation of Vertebrates. Verlag Dr. Friedrich Pfeil, 2004.
  2. 1 2 3 4 5 6 Spindler, F.; Scott, Diane; Reisz, Robert (October 2014). "New information on the cranial and postcranial anatomy of the early synapsid Ianthodon schultzei (Sphenacomorpha: Sphenacodontia), and its evolutionary significance". Fossil Record. 18: 17–30.
  3. 1 2 Currie, P. J.: A new haptodontine sphenacodont (Reptilia: Pelycosauria) from the Upper Pennsylvanian of North America, J. Paleontol., 51, 927–942, 1977
  4. Reisz, Robert R.; Heaton, Malcolm J.; Pynn, Bruce R. (1982). "Vertebrate Fauna of Late Pennsylvanian Rock Lake Shale near Garnett, Kansas: Pelycosauria". Journal of Paleontology. 56 (3): 741–750. JSTOR   1304403.
  5. 1 2 Roger B. J. Benson (2012) Interrelationships of basal synapsids: cranial and postcranial morphological partitions suggest different topologies, Journal of Systematic Palaeontology, 10:4, 601-624, DOI: 10.1080/14772019.2011.631042
  6. 1 2 Laurin, Michel (1993). "Anatomy and Relationships of Haptodus garnettensis, a Pennsylvanian Synapsid from Kansas". Journal of Vertebrate Paleontology. 13 (2): 200–229. doi:10.1080/02724634.1993.10011501. JSTOR   4523501.
  7. Fröbisch, Jörg; Schoch, Rainer R.; Müller, Johannes; Schindler, Thomas; Schweiss, Dieter (March 2011). "A New Basal Sphenacodontid Synapsid from the Late Carboniferous of the Saar-Nahe Basin, Germany". Acta Palaeontologica Polonica. 56 (1): 113–120. doi: 10.4202/app.2010.0039 . ISSN   0567-7920.