# Calamosuchus

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Genus of phytosaur reptiles

Not to be confused with [Calmasuchus](/source/Calmasuchus).

Calamosuchus Temporal range: Late Triassic, Carnian (Tuvalian substage) PreꞒ Ꞓ O S D C P T J K Pg N Holotype specimen, labeled as Belodon (=Nicrosaurus) kapffi Scientific classification Kingdom: Animalia Phylum: Chordata Class: Reptilia Clade: Crurotarsi Order: †Phytosauria Clade: †incertae sedis Genus: †Calamosuchus Sues & Schoch, 2025 Species: †C. arenaceus Binomial name †Calamosuchus arenaceus (Fraas, 1896) Synonyms[1] Zanclodon arenaceus Fraas, 1896 Belodon arenaceus (Fraas, 1896) Huene, 1902 Phytosaurus arenaceus (Fraas, 1896) Schmidt, 1928 Mystriosuchus arenaceus (Fraas, 1896) Kühn, 1933

***Calamosuchus*** is an [extinct](/source/Extinct) genus of probable early [phytosaurian](/source/Phytosauria) reptiles known from the [Late Triassic](/source/Late_Triassic) ([Carnian](/source/Carnian) age) [Stuttgart Formation](/source/Stuttgart_Formation) of Germany. The genus contains a [single species](/source/Monotypic_taxon), ***Calamosuchus arenaceus***, known from a partial [mandible](/source/Mandible). The species was first described in 1896 by [Eberhard Fraas](/source/Eberhard_Fraas), who assigned it to the genus *[Zanclodon](/source/Zanclodon)* as *Z. arenaceus*. Although researchers have noticed substantial differences between *Z. arenaceus* and the *Z. laevis* (the [type species](/source/Type_species)) since 1902, it did not receive a distinct genus name until 2025, when it was placed in the new genus *Calamosuchus*.

## Discovery and naming

In 1869, the [State Museum of Natural History Stuttgart](/source/State_Museum_of_Natural_History_Stuttgart) (SMNS) obtained a partial [mandible](/source/Mandible) collected by Sixt Friedrich Jakob von Kapff, at which point it was identified as a specimen of *[Belodon](/source/Belodon)* (now *[Nicrosaurus](/source/Nicrosaurus)*) *kapffi*. The specimen was discovered in the Schilfsandstein ('reed sandstone') deposits in [Feuerbacher Heide](https://de.wikipedia.org/wiki/Feuerbacher_Heide), representing outcrops of the [Stuttgart Formation](/source/Stuttgart_Formation) near [Feuerbach, Stuttgart](/source/Stuttgart-Feuerbach), in Germany. The specimen is permanently [accessioned](/source/Accession_number_(cultural_property)) at this museum as specimen SMNS 80737.[2][1][3]

In 1896, German paleontologist [Eberhard Fraas](/source/Eberhard_Fraas) provided the first brief description of SMNS 80737, naming it as the [holotype](/source/Holotype) of a new species of the genus *[Zanclodon](/source/Zanclodon)*, *Z. arenaceus*, at that time thought—according to Fraas—to be a [dinosaur](/source/Dinosaur) without any doubt.[2] The [specific name](/source/Specific_name_(zoology)), *arenaceus*, is a [Latin](/source/Latin) word referring to sandy places,[4] alluding to the discovery of the specimen in the Schilfsandstein locality, literally translating to 'reed sandstone'.[3]

In subsequent years, publications by researchers including [Friedrich von Huene](/source/Friedrich_von_Huene) in 1902 and Frank Westphal in 1963 regarded the specimen as belonging to a member of the [Phytosauria](/source/Phytosauria)—a group of [convergently](/source/Convergent_evolution) crocodilian-like [archosauriforms](/source/Archosauriform)—instead of a dinosaur.[3] Von Huene provided the first published figure of SMNS 80737, criticizing Fraas' identification of the specimen. Although he provided no anatomical evidence for his conclusions, he assigned the species to the phytosaur genus *Belodon*. Later researchers accepted a phtyosaur placement for the species, not part of the genus *Zanclodon*, proposing affinities with the genera *[Phytosaurus](/source/Phytosaurus)* and *[Mystriosuchus](/source/Mystriosuchus)* as well. The first detailed description of SMNS 80737 was provided by Axel Hungerbühler in 2001, who confirmed the specimen is significantly distinct from *Z. laevis*, the [type species](/source/Type_species) of *Zanclodon*, and concluded it should not be treated as a member of this genus. Hungerbühler further noted phytosaur-like characters in the specimen, but also the lack of important phytosaur [autapomorphies](/source/Autapomorphies) (unique derived traits). As such, "*Z.*" *arenaceus* was treated as Archosauria *[incertae sedis](/source/Incertae_sedis)*. Hungerbühler refrained from naming a new genus for the material due to its fragmentary nature.[1]

In 2025, [Hans-Dieter Sues](/source/Hans-Dieter_Sues) and Rainer R. Schoch published an extensive review of Triassic reptiles from Germany. Herein, they proposed a new genus name for "*Z.*" *arenaceus*, forming the new combination *Calamosuchus arenaceus*. The new [generic name](/source/Genus), *Calamosuchus*, combines *calamus*, a Latin word meaning 'reed', with the [Greek](/source/Greek_language) word *soûkhos* (*suchus*), derived from the Greek name of [Sobek](/source/Sobek), the crocodile-headed [deity of Ancient Egyptian myth](/source/Ancient_Egyptian_deities). Like the specific name, this references the Schilfsandstein locality where the holotype was found, while '-suchus' is a suffix often used in reptile generic names.[3]

## Description and classification

The preserved mandible of *Calamosuchus* measures about 23 centimetres (9.1 in) long, including at least the [dentaries](/source/Mandible#Phylogeny) and [splenials](/source/Splenial). The [symphysis](/source/Mandibular_symphysis) (region where the two hemimandibles fuse at the midline) is 11.5 cm (4.5 in) long. The morphology of the fragmentary specimen indicates the mandible would have been greatly elongate in life. All of the visible teeth are incomplete; the right side has 15 [alveoli](/source/Alveoli) (tooth positions) and nine preserved teeth. The teeth bear serrations, contrary to the condition in *Zanclodon laevis*, which lacks them.[1]

In the 2001 redescription of SMNS 80737, a [phylogenetic analysis](/source/Phylogenetic_analysis) was performed, recovering the specimen as the [sister taxon](/source/Sister_taxon) to [Phytosauria](/source/Phytosauria). However, Hungerbühler noted that, while this is the most parsimonious (best supported by the available data) position in the analysis, many characters separate it from phytosaurs and all other Triassic archosaurs studied at that time. The only characters he observed uniting "*Z.*" *arenaceus* with phytosaurs is the elongated mandible and mandibular symphysis, while it is different in all other features. Differences include the shape and proportional height of the mandible, the anterior (toward the tip of the snout) extent of the splenial, the tooth structure, and the absence of [heterodonty](/source/Heterodonty) (multiple tooth morphologies). As such, the species could not be assigned to the Phytosauria based on its definition at the time, and Hungerbühler refrained from redefining the clade to include "*Z.*" *arenaceus*. Instead, he treated it more broadly as a member of the [Archosauria](/source/Archosauria) with uncertain placement (*[incertae sedis](/source/Incertae_sedis)*).[1]

In their 2025 publication naming the new genus *Calamosuchus* for "*Z.*" *arenaceus*, Sues and Schoch instead described it as Phytosauria *incertae sedis*, suggesting it represents an early-diverging member of this clade.[3]

## Palaeoenvironment

*Calamosuchus* is known from the [Stuttgart Formation](/source/Stuttgart_Formation), which dates to the [Carnian](/source/Carnian) age of the [Late Triassic](/source/Late_Triassic). Other reptiles known from this formation include *[Henodus chelyops](/source/Henodus_chelyops)* (a [turtle](/source/Turtle)-like [placodontian](/source/Placodontia) [sauropterygian](/source/Sauropterygia)), *[Thuringopelta werneburgi](/source/Thuringopelta_werneburgi)* (a [doswelliid](/source/Doswelliid) [proterochampsian](/source/Proterochampsia)), and *[Dyoplax arenaceus](/source/Dyoplax_arenaceus)* (an [erpetosuchid](/source/Erpetosuchid) [pseudosuchian](/source/Pseudosuchia)).[3]

## References

1. ^ [***a***](#cite_ref-A.H.2001_1-0) [***b***](#cite_ref-A.H.2001_1-1) [***c***](#cite_ref-A.H.2001_1-2) [***d***](#cite_ref-A.H.2001_1-3) [***e***](#cite_ref-A.H.2001_1-4) Hungerbühler, Axel (August 2001). "The status and phylogenetic relationships of "*Zanclodon*" *arenaceus*: the earliest known phytosaur?". *[Paläontologische Zeitschrift](/source/Pal%C3%A4ontologische_Zeitschrift)*. **75** (1): 97–112. [doi](/source/Doi_(identifier)):[10.1007/BF03022600](https://doi.org/10.1007%2FBF03022600). [ISSN](/source/ISSN_(identifier)) [0031-0220](https://search.worldcat.org/issn/0031-0220).

1. ^ [***a***](#cite_ref-Fraas1996_2-0) [***b***](#cite_ref-Fraas1996_2-1) [Fraas, Eberhard](/source/Eberhard_Fraas) (1896). [*Die schwäbischen Trias-Saurier, nach dem Material der Kgl. Naturalien-Sammlung in Stuttgart zusammengestellt*](https://hdl.handle.net/2027/uc1.c046894297) (in German). Stuttgart: E. Schweizerbart'sche Verlagsbuchhandlung. pp. 1–18.

1. ^ [***a***](#cite_ref-S&S25_3-0) [***b***](#cite_ref-S&S25_3-1) [***c***](#cite_ref-S&S25_3-2) [***d***](#cite_ref-S&S25_3-3) [***e***](#cite_ref-S&S25_3-4) [***f***](#cite_ref-S&S25_3-5) Sues, Hans-Dieter; Schoch, Rainer R. (2025-12-04). ["Synopsis of the Triassic reptiles from Germany"](https://doi.org/10.3897%2Ffr.28.164405). *Fossil Record*. **28** (2): 411–483. [doi](/source/Doi_(identifier)):[10.3897/fr.28.164405](https://doi.org/10.3897%2Ffr.28.164405). [ISSN](/source/ISSN_(identifier)) [2193-0074](https://search.worldcat.org/issn/2193-0074).

1. **[^](#cite_ref-M-W_4-0)** ["arenaceous"](https://www.merriam-webster.com/dictionary/arenaceous). *[Merriam-Webster.com Dictionary](/source/Merriam-Webster)*. Merriam-Webster. [OCLC](/source/OCLC_(identifier)) [1032680871](https://search.worldcat.org/oclc/1032680871). Retrieved 2025-12-07.

v t e Phytosauria Kingdom: Animalia Phylum: Chordata Class: Sauropsida Clade: Archosauromorpha Clade: Crurotarsi Sauropsida see Sauropsida Archosauromorpha see Archosauromorpha Phytosauria see below↓ Phytosauria Phytosauria Calamosuchus Diandongosuchus Heteropelta? Parasuchidae Arganarhinus Ebrachosuchus Paleorhinus Parasuchus Wannia Mystriosuchinae / Phytosauridae Angistorhinus Brachysuchus Colossosuchus Jupijkam Protome Rutiodon Volcanosuchus Leptosuchomorpha Leptosuchus Pravusuchus Smilosuchus Mystriosuchini Angistorhinopsis Machaeroprosopus Mystriosuchus Nicrosaurus Redondasaurus Nomina dubia Belodon Centemodon Clepsysaurus? Coburgosuchus Compsosaurus Francosuchus Heterodontosuchus Mesorhinosuchus Omosaurus? Palaeoctonus? Phytosaurus Rileyasuchus Suchoprion Termatosaurus? Category

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