# Polesinesuchus

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Extinct genus of reptiles

Polesinesuchus Temporal range: Late Triassic ~231.4–225.9 Ma PreꞒ Ꞓ O S D C P T J K Pg N Skeletal diagram of the holotype of Polesinesuchus Scientific classification Kingdom: Animalia Phylum: Chordata Class: Reptilia Clade: Pseudosuchia Order: †Aetosauria Family: †Stagonolepididae Genus: †Polesinesuchus Roberto-da-Silva et al. 2014 Type species †Polesinesuchus aurelioi Roberto-da-Silva et al. 2014

***Polesinesuchus*** is an [extinct](/source/Extinct) [genus](/source/Genus) of [stagonolepidid](/source/Stagonolepidid) [aetosaur](/source/Aetosaur) known from the [Late Triassic](/source/Late_Triassic) of southern [Brazil](/source/Brazil). Fossils have been found from the [Santa Maria Supersequence](/source/Santa_Maria_Formation) of the late [Carnian](/source/Carnian) and early [Norian](/source/Norian) stages, making *Polesinesuchus* one of the oldest aetosaurs. It contains a single species, ***Polesinesuchus aurelioi***, the fifth aetosaur species known from [South America](/source/South_America) to date.[1] Anatomical evidence suggests that *Polesinesuchus* likely represents a juvenile individual of the contemporary *[Aetosauroides](/source/Aetosauroides)*.[2][3]

## Discovery

*Polesinesuchus* was first named by Lúcio Roberto-da-Silva, Julia B. Desojo, Sérgio F. Cabreira, Alex S. S. Aires, Rodrigo T. Müller, Cristian P. Pacheco and Sérgio Dias-da-Silva in [2014](/source/2014_in_paleontology) and the [type species](/source/Type_species) is *Polesinesuchus aurelioi*. It is known solely from its [holotype](/source/Holotype) specimen, a partially articulated partial [skeleton](/source/Skeleton). It is composed of the [parietal bone](/source/Parietal_bone) and the [braincase](/source/Neurocranium) as well as [postcranial](/source/Postcrania) elements including [cervical](/source/Cervical_vertebrae), [dorsal](/source/Dorsal_vertebrae), [sacral](/source/Sacral_vertebrae) and [caudal vertebrae](/source/Caudal_vertebrae), both [scapulae](/source/Scapula), a [humerus](/source/Humerus), the [ilium](/source/Ilium_(bone)), [pubis](/source/Pubis_(bone)), [ischium](/source/Ischium) and [tibia](/source/Tibia), a partial right pes, and anterior and mid-dorsal paramedian [osteoderms](/source/Osteoderm). It was collected from the [Santa Maria Formation](/source/Santa_Maria_Formation) which dates back to the late [Carnian](/source/Carnian) and earliest [Norian](/source/Norian) stages of the [Late Triassic](/source/Late_Triassic).[1]

## Description

*Polesinesuchus* is known from a relatively small-sized individual with an estimated length of 76 centimetres (30 in), probably a two-year-old [juvenile](/source/Juvenile_(organism)) based on the incomplete fusion of neural arches to their [centra](/source/Body_of_vertebra) in the whole [vertebral column](/source/Vertebral_column).[2] *Polesinesuchus* can be distinguished from all other [aetosaurs](/source/Aetosaur) by a unique combination of characters not controlled by [ontogeny](/source/Ontogeny), most of which are found in its vertebrae. Its [cervical vertebrae](/source/Cervical_vertebrae) show [prezygapophyses](/source/Articular_processes) that widely extend laterally through most of the anterior edge of the [diapophyses](https://en.wiktionary.org/wiki/diapophyses). In *Polesinesuchus*, [hyposphene articulations](/source/Hyposphene-hypantrum_articulation) are absent in both cervical and mid-[dorsal vertebrae](/source/Dorsal_vertebrae). A ventral keel is present in the cervical vertebrae. The [centra](/source/Body_of_vertebra) of the anterior and mid-dorsal vertebrae lack a lateral [fossa](/source/Fossa_(anatomy)). The proximal end of the [scapula](/source/Scapula) is greatly expanded, while the medial portion of scapular blade is expanded anteroposteriorly. *Polesinesuchus* possess a short [humerus](/source/Humerus) with a robust shaft, and a dorsoventral and very low iliac blade with a long anterior process, exceeding slightly the pubic peduncle.[1] Yet, in 2021, it was found that many of these features fall within the range of variation present in juvenile specimens of *[Aetosauroides](/source/Aetosauroides)*. One example is the lateral fossa, which becomes more apparent in individuals of *Aetosauroides* longer than 1 metre (3 ft 3 in)).[2] Furthermore, a braincase of *Aetosauroides* had a remarkably similar structure of the basioccipital bone to *Polesinesuchus*.[3] For these reasons, *Polesinesuchus* was suggested as a junior synonym of *Aetosauroides*.[2]

## Classification

A [phylogenetic](/source/Phylogenetic) analysis was conducted in the first description of *Polesinesuchus* based on a slightly updated data matrix from previous analyses, resulting in a matrix that includes 19 aetosaurs and two outgroup taxa which are scored based on 37 morphological traits. *Polesinesuchus* was recovered as the [sister taxon](/source/Sister_taxon) of *[Aetobarbakinoides](/source/Aetobarbakinoides)*, known from the same [geological formation](/source/Formation_(stratigraphy)). Close relatives of this [clade](/source/Clade) included *Aetosauroides* and *[Neoaetosauroides](/source/Neoaetosauroides)*, both of which are also from South America. However, [Aetosaurinae](/source/Aetosaurinae) is found to be [paraphyletic](/source/Paraphyletic) representing a [grade](/source/Evolutionary_grade) of early aetosaurs that developed into desmatosuchines and typothoracisines later in the Triassic. Although this clade is placed in a relatively [basal](/source/Basal_(phylogenetics)) [phylogenetic](/source/Phylogenetic) position among [stagonolepidid](/source/Stagonolepidid) aetosaurs, it is closely related to both [desmatosuchines](/source/Desmatosuchine) and [typothoracisines](/source/Typothoracisine), two derived clades of stagonolepidids. Below is a [cladogram](/source/Cladogram) modified from this analysis.[1]

Aetosauria Aetosauroides scagliai Stagonolepididae Aetosaurus ferratus Coahomasuchus kahleorum Neoaetosauroides engaeus Calyptosuchus wellesi Stagonolepis robertsoni Aetobarbakinoides brasiliensis Polesinesuchus aurelioi Typothoracisinae Typothorax Redondasuchus Paratypothoracisini Tecovasuchus chatterjeei Rioarribasuchus chamaensis Paratypothorax andressorum Desmatosuchinae Sierritasuchus macalpini Longosuchus meadei Lucasuchus hunti Acaenasuchus geoffreyi Desmatosuchus Desmatosuchus haplocerus Desmatosuchus smalli

## See also

- [Brazil portal](https://en.wikipedia.org/wiki/Portal:Brazil)
- [Paleontology portal](https://en.wikipedia.org/wiki/Portal:Paleontology)

- *[Buriolestes](/source/Buriolestes)*

- *[Ixalerpeton](/source/Ixalerpeton)*

## References

1. ^ [***a***](#cite_ref-Polesinesuchus_1-0) [***b***](#cite_ref-Polesinesuchus_1-1) [***c***](#cite_ref-Polesinesuchus_1-2) [***d***](#cite_ref-Polesinesuchus_1-3) Roberto-Da-Silva, L. C.; Desojo, J. B.; Cabreira, S. R. F.; Aires, A. S. S.; Müller, R. T.; Pacheco, C. P.; Dias-Da-Silva, S. R. (2014). ["A new aetosaur from the Upper Triassic of the Santa Maria Formation, southern Brazil"](https://www.researchgate.net/publication/262696630). *Zootaxa*. **3764** (3): 240–278. [doi](/source/Doi_(identifier)):[10.11646/zootaxa.3764.3.1](https://doi.org/10.11646%2Fzootaxa.3764.3.1). [hdl](/source/Hdl_(identifier)):[11336/20729](https://hdl.handle.net/11336%2F20729). [PMID](/source/PMID_(identifier)) [24870635](https://pubmed.ncbi.nlm.nih.gov/24870635).

1. ^ [***a***](#cite_ref-paesneto2021axial_2-0) [***b***](#cite_ref-paesneto2021axial_2-1) [***c***](#cite_ref-paesneto2021axial_2-2) [***d***](#cite_ref-paesneto2021axial_2-3) Paes-Neto, V.D.; Desojo, J.B.; Brust, A.C.B.; Schultz, C.L.; Da-Rosa, A.A.S.; Soares, M.B. (2021). "Intraspecific variation in the axial skeleton of *Aetosauroides scagliai* (Archosauria: Aetosauria) and its implications for the aetosaur diversity of the Late Triassic of Brazil". *Annals of the Brazilian Academy of Sciences*. **93** (supp. 2) e20201239. [doi](/source/Doi_(identifier)):[10.1590/0001-3765202120201239](https://doi.org/10.1590%2F0001-3765202120201239). [hdl](/source/Hdl_(identifier)):[11336/150258](https://hdl.handle.net/11336%2F150258). [PMID](/source/PMID_(identifier)) [34468486](https://pubmed.ncbi.nlm.nih.gov/34468486). [S2CID](/source/S2CID_(identifier)) [237372648](https://api.semanticscholar.org/CorpusID:237372648).

1. ^ [***a***](#cite_ref-paesneto2021bc_3-0) [***b***](#cite_ref-paesneto2021bc_3-1) Paes-Neto, V.D.; Desojo, J.B.; Brust, A.C.B.; Ribeiro, A.M.; Schultz, C.L.; Soares, M.B. (2021). "The first braincase of the basal aetosaur *Aetosauroides scagliai* (Archosauria: Pseudosuchia) from the Upper Triassic of Brazil". *Journal of Vertebrate Paleontology*. **41** (2) e1928681. [doi](/source/Doi_(identifier)):[10.1080/02724634.2021.1928681](https://doi.org/10.1080%2F02724634.2021.1928681). [S2CID](/source/S2CID_(identifier)) [237518035](https://api.semanticscholar.org/CorpusID:237518035).

v t e Aetosauria Kingdom: Animalia Phylum: Chordata Class: Sauropsida Clade: Pseudosuchia Clade: Aetosauriformes Pseudosuchia see Pseudosuchia Aetosauria see below↓ Aetosauria †Aetosauria Aetosauroides Stagonolepididae Aetosaurinae Aetosaurus Coahomasuchus? Stenomyti? Typothoracinae? Apachesuchus Chilenosuchus? Gorgetosuchus? Kryphioparma Redondasuchus Typothorax Paratypothoracini Garzapelta? Kocurypelta Kuttysuchus Paratypothorax Rioarribasuchus Tecovasuchus Venkatasuchus Desmatosuchia Stagonolepidinae? Polesinesuchus Stagonolepis Desmatosuchinae sensu lato Adamanasuchus? Aetobarbakinoides? Calyptosuchus? Chilenosuchus? Neoaetosauroides? Olkasuchus Scutarx? Desmatosuchini (Desmatosuchinae sensu stricto) Desmatosuchus Gorgetosuchus? Longosuchus Lucasuchus Sierritasuchus Category

Taxon identifiers Polesinesuchus Wikidata: Q15726984 Wikispecies: Polesinesuchus GBIF: 8438088 IRMNG: 1483593 Open Tree of Life: 6149724 Paleobiology Database: 333722

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Adapted from the Wikipedia article [Polesinesuchus](https://en.wikipedia.org/wiki/Polesinesuchus) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Polesinesuchus?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.