# Desmatosuchus

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Extinct genus of reptiles

Desmatosuchus Temporal range: Late Triassic (Carnian to Norian), 228–210 Ma PreꞒ Ꞓ O S D C P T J K Pg N A mounted Desmatosuchus replica skeleton on display at the Houston Museum of Natural Science Scientific classification Kingdom: Animalia Phylum: Chordata Class: Reptilia Clade: Pseudosuchia Order: †Aetosauria Family: †Stagonolepididae Subfamily: †Desmatosuchinae Genus: †Desmatosuchus Case, 1920 Type species †Desmatosuchus spurensis Case, 1921 Species †D. spurensis Case, 1921 †D. smalli Parker, 2005[1] Synonyms Episcoposaurus haplocerus Cope, 1892

***Desmatosuchus*** ([/dɛzmætoʊsuːkəs/](https://en.wikipedia.org/wiki/Help:IPA/English), from [Greek](/source/Greek_language) δεσμός *desmos* 'link' + σοῦχος *soûkhos* 'crocodile') is an [extinct](/source/Extinct) [genus](/source/Genus) of [archosaur](/source/Archosaur) belonging to the Order [Aetosauria](/source/Aetosauria). It lived in North America and potentially India (cf. *Desmatosuchus*) during the [Late Triassic](/source/Late_Triassic).[2]

## Description

*D. spurensis* compared to a human

*Desmatosuchus* was a large quadrupedal reptile measuring 4.5 m (15 ft) to over 5 m (16 ft) long and weighing about 280–300 kg (620–660 lb).[3][4][5][6] Its [vertebral column](/source/Vertebral_column) had amphicoelous [centra](/source/Vertebra) and 3 sacral vertebrae. This archosaur's most distinguishing anatomical characteristics were its [scapulae](/source/Scapula) which possessed large [acromion processes](/source/Acromion) commonly referred to as "shoulder spikes".[3] The forelimbs were much shorter than the hindlimbs, with [humeri](/source/Humerus) less than two-thirds the length of the [femurs](/source/Femur).[7] The [pelvic girdle](/source/Pelvis) consisted of a long [pubis](/source/Pubis_(bone)) with a strong [symphysis](/source/Symphysis) in the middle, a plate-like [ischium](/source/Ischium), a highly recurved [ilium](/source/Ilium_(bone)), and a deep, imperforate [acetabulum](/source/Acetabulum).[7] The femurs were relatively long and straight, the ankles [crurotarsal](/source/Crurotarsal), with [calcaneal](/source/Calcaneal) tubers that gave it large heels.[7]

*Desmatosuchus* skeleton on display at the [University of Michigan Museum of Natural History](/source/University_of_Michigan_Museum_of_Natural_History)

Its skull was relatively small, on average about 37 centimeters long, 18 centimeters wide, and 15 centimeters high. The braincase was very firmly fused with the skull roof and palate. It had slender, forked [premaxillae](/source/Premaxilla) that turned up and expanded in the front, creating a shovel-like structure.[3] *Desmatosuchus* is unique among aetosaurs in that its species are the only known aetosaurs that lacked teeth on their premaxillae.[3] Their premaxillae fit loosely together with their [maxillae](/source/Maxilla), indicating flexibility at that joint.[3] Their maxilla contained 10 to 12 teeth.[3] *Desmatosuchus* also had very thin [vomers](/source/Vomer), which bounded the medial side of the [internal nares](/source/Internal_nares).[3] These internal nares were relatively large, roughly half the length of the entire palate.[3] The lower jaw typically carried 5 or 6 teeth, and had a toothless beak on the end.[3] The [dentary](/source/Dentary) was about half the length of the lower jaw, with the front portion being toothless and covered by a horny sheath.[3] Behind the dentary was a moderately large mandibular [fenestra](/source/Fenestra_(anatomy)).

Individuals of *Desmatosuchus* were heavily armored. The [carapace](/source/Carapace) was made up of two rows of median [scutes](/source/Scute) surrounded by two more rows of lateral scutes. The lateral scutes had well-developed spine-like [processes](/source/Process_(anatomy)) which pointed out laterally and dorso-posteriorly.[8] There were typically five rows of spines, increasing in size anteriorly. The front spine was much larger, around 28 centimeters long, and was recurved. The fourth spine varies in length in each specimen, but remains shorter than the fifth in all of them.[3] *Desmatosuchus* are the only aetosaurs known to have possessed spines like these.[8]

## Discovery and classification

The first *Desmatosuchus* discovery occurred in the late 19th century when [E.D. Cope](/source/Edward_Drinker_Cope) classified armor from the [Dockum Group](/source/Dockum_Group) in [Texas](/source/Texas), USA, as the new species *Episcoposaurus haplocerus*.[9] Case later classified a partial skeleton found in the [Tecovas Formation](/source/Tecovas_Formation) as *Desmatosuchus spurensis*.[10] Since the localities of Cope and Case were only a few kilometers apart, the two taxa were synonymized into *Desmatosuchus haplocerus*, the initial type species of the genus.[9]

A revision of *Desmatosuchus* by Parker (2008) found the [lectotype](/source/Type_(biology)#Lectotype) of *Episcoposaurus haplocerus* to be referable to *Desmatosuchus* but indeterminate at the species level. Therefore, *E. haplocerus* was considered to be a *[nomen dubium](/source/Nomen_dubium)* and *D. spurensis* was named the [type species](/source/Type_species) of the genus. Two species were accepted as valid: *D. spurensis* and *D. smalli*, named after Brian J. Small for his contribution to the study of this genus.[11] *Desmatosuchus chamaensis* is recognized as a distinct genus, but there is some dispute about whether the name *[Heliocanthus](/source/Heliocanthus)* or *[Rioarribasuchus](/source/Rioarribasuchus)* applies.[9]

The following [cladogram](/source/Cladogram) is simplified, after an analysis presented by Julia B. Desojo, Martin D. Ezcurra and Edio E. Kischlat (2012).[12]

*Desmatosuchus* skeleton from the [University of Michigan Museum of Natural History](/source/University_of_Michigan_Museum_of_Natural_History)

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

## Paleobiology

*D. haplocerus* from the Late Triassic of Texas

Bones and armor pieces of *Desmatosuchus* are abundant in the Dockum formation, [Chinle](/source/Chinle_Formation) formation, and Post quarry, indicating that they were widespread and abundant during the Late Triassic.[3] It is possible that *Desmatosuchus* traveled in herds or family units. This is evidenced by several findings of multiple *Desmatosuchus* skeletons in relatively small areas.[3]

*Desmatosuchus* had blunt, bulbous, slightly recurved teeth. Furthermore, they are believed to have had [homodont](/source/Homodont) dentition.[3] This, combined with its shovel like snout, indicate that *Desmatosuchus* fed by digging up soft vegetation.[8] This method of feeding is further evidenced by its toothless premaxilla and dentary tip, which were covered in horny sheaths. These sheaths protected the bones and could be used for cutting or holding objects.[13] It is believed that *Desmatosuchus* dug for food in the soft mud near bodies of water due to the abundance of lakes and rivers in the Dockum area and the fact that *Desmatosuchus* scutes are often found among parts of other reptiles that are known to have fed along waterways.[3] It is unknown whether or not *Desmatosuchus* replaced their teeth and, if so, how. The low number of *Desmatosuchus* teeth that have been discovered indicates that they were only held in place by soft tissue connections.[3] The jaw articulation point is below the tooth line, holding its upper and lower tooth rows parallel while biting in a way that is reminiscent of [ornithischian](/source/Ornithischian) dinosaurs.[13]

*[Postosuchus](/source/Postosuchus)* and *Desmatosuchus*

The armor and spikes of *Desmatosuchus* were its only ways to defend itself from predators. The lateral spike rows showed variation in size among individuals, especially the second most anterior spike. This spike was always shorter than the one in front of it, but to what extent varied drastically. This variation may indicate [sexual dimorphism](/source/Sexual_dimorphism).[8] It has also been hypothesized as a form of sexual display.[3] Aside from this armor, *Desmatosuchus* was defenseless from attacks from carnivores. Several *Desmatosuchus* bones have been found amongst skeletons of *[Postosuchus](/source/Postosuchus)*, indicating predation by *Postosuchus*.[3] The herd nature of *Desmatosuchus* apparently did little to discourage predators, as *Postosuchus* along with several other Late Triassic carnivores also traveled in groups.[3]

Most thecodonts of the Late Triassic lacked certain pelvic features that aided locomotion, such as a deep acetabulum or a crest over the acetabulum. This, in spite of their upright posture, rendered them only slightly more mobile than sprawling reptiles.[14] *Desmatosuchus* possessed both of these features, along with its long femur and elongate pubis, making it more mobile than most thecodonts of its time.[14] This mobility, along with its size, abundance, and specialized beak made it the chief herbivore in the Dockum area.[3]

It has also been suggested that *Desmatosuchus* could have been omnivorous or even an insectivore. This is because of several similarities between *Desmatosuchus* and [armadillos](/source/Armadillos).[15] For instance, both groups are armored. They possess long snouts that lack teeth on the end. Also, there is evidence of bees, wasps, and termites in the Late Triassic, meaning that *Desmatosuchus* had access to insects that armadillos prey on.[15] Their teeth are somewhat similar in shape, although armadillos have more peg-like teeth.[15] Both *Desmatosuchus* and armadillos typically carry around 6 teeth on their dentaries. Both armadillos and *Desmatosuchus* have hypertrophied processes present on their limb bones, which indicates large limb muscles.[15] This connection is more tenuous, however, since *Desmatosuchus* have a crest over their hind limbs but lack one on their forelimbs, meaning that they likely didn't have the musculature for digging with their forelimbs the way armadillos do. In spite of these parallels, the general consensus is still that *Desmatosuchus* was most likely herbivorous.[3] [14]

## References

1. **[^](#cite_ref-Parker,_2005_1-0)** Parker, William G. (June 2005). "A new species of the Late Triassic aetosaur *Desmatosuchus* (Archosauria: Pseudosuchia)". *[Comptes Rendus Palevol](/source/Comptes_Rendus_Palevol)*. **4** (4): 327–340. [doi](/source/Doi_(identifier)):[10.1016/j.crpv.2005.03.002](https://doi.org/10.1016%2Fj.crpv.2005.03.002).

1. **[^](#cite_ref-2)** Haldar, A.; Ray, S.; Bandyopadhyay, S. (2025). "First report of desmatosuchin aetosaurs (Diapsida, Archosauria) from the lower part of Dharmaram Formation and a biostratigraphic re-evaluation of the upper Triassic horizons of India". *Historical Biology: An International Journal of Paleobiology*: 1–30. [doi](/source/Doi_(identifier)):[10.1080/08912963.2025.2569748](https://doi.org/10.1080%2F08912963.2025.2569748).

1. ^ [***a***](#cite_ref-small_3-0) [***b***](#cite_ref-small_3-1) [***c***](#cite_ref-small_3-2) [***d***](#cite_ref-small_3-3) [***e***](#cite_ref-small_3-4) [***f***](#cite_ref-small_3-5) [***g***](#cite_ref-small_3-6) [***h***](#cite_ref-small_3-7) [***i***](#cite_ref-small_3-8) [***j***](#cite_ref-small_3-9) [***k***](#cite_ref-small_3-10) [***l***](#cite_ref-small_3-11) [***m***](#cite_ref-small_3-12) [***n***](#cite_ref-small_3-13) [***o***](#cite_ref-small_3-14) [***p***](#cite_ref-small_3-15) [***q***](#cite_ref-small_3-16) [***r***](#cite_ref-small_3-17) [***s***](#cite_ref-small_3-18) [***t***](#cite_ref-small_3-19) [***u***](#cite_ref-small_3-20) Small, Bryan John (December 1985). *The Triassic thecodontian reptile Desmatosuchus: osteology and relationships* (Masters thesis). [Texas Tech University](/source/Texas_Tech_University). [hdl](/source/Hdl_(identifier)):[2346/19710](https://hdl.handle.net/2346%2F19710).

1. **[^](#cite_ref-Baczko2021_4-0)** von Baczko, M. B., Desojo, J. B., Gower, D. J., Ridgely, R., Bona, P., & Witmer, L. M. (2021). [New digital braincase endocasts of two species of Desmatosuchus and neurocranial diversity within Aetosauria (Archosauria: Pseudosuchia)](https://www.researchgate.net/publication/355407927_New_digital_braincase_endocasts_of_two_species_of_Desmatosuchus_and_neurocranial_diversity_within_Aetosauria_Archosauria_Pseudosuchia). The Anatomical Record, 1–20. [https://doi.org/10.1002/ar.24798](https://doi.org/10.1002/ar.24798)

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Taxon identifiers Desmatosuchus Wikidata: Q132727 Wikispecies: Desmatosuchus GBIF: 4818077 IRMNG: 1272575 Open Tree of Life: 4127068 Paleobiology Database: 38275

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