Clarkeiteuthis
{{Short description|Extinct genus of molluscs}}
{{Automatic taxobox
| fossil_range = Hettangian to Toarcian {{Fossil range|Hettangian|180}}
| image = Clarkeiteuthis with Leptolepis fossil.png
| image_caption = Fossil of Clarkeiteuthis conocauda preying on Leptolepis
| taxon = Clarkeiteuthis
| authority = Dirk et al. 2013
| subdivision_ranks = Species
| subdivision = *C. conocauda Quenstedt, 1849
- C. montefiorei Buckman, 1880
| synonyms = Synonyms of C. conocauda
- Onychoteuthis conocauda Quenstedt, 1849
- Acanthoteuthis conocauda (Quenstedt, 1849)
- Phragmoteuthis conocauda (Quenstedt, 1849)
Synonyms of C. montefiorei
- Belemnoteuthis montefiorei Buckman, 1880
- Acanthoteuthis montefiorei (Buckman, 1880)
- Phragmoteuthis montefiorei (Buckman, 1880)
}}
Clarkeiteuthis is a genus of extinct belemnoid cephalopod known from the lower Jurassic in Germany and England. Described two species, C. conocauda and C. montefiorei are originally described as species of phragmoteuthid Phragmoteuthis, but got their own genus and moved to Diplobelida.{{Cite journal |last1=Fuchs |first1=Dirk |last2=Donovan |first2=Desmond T. |last3=Keupp |first3=Helmut |date=2013-12-01 |title=Taxonomic revision of ?Onychoteuthis? conocauda Quenstedt, 1849 (Cephalopoda: Coleoidea) |url=https://www.researchgate.net/publication/272205098 |journal=Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen |volume=270 |issue=3 |language=en |pages=245–255 |doi=10.1127/0077-7749/2013/0368}}
Description
File:Phragmoteuthis conocauda.JPG
Two species are described, C. conocauda is known from Posidonia Shale, and C. montefiorei is known from the Hettangian strata of the Blue Lias Formation{{Cite journal|last1=Evans |first1=David H. |last2=Klug |first2=Christian |last3=King |first3=Andrew H. |last4=Page |first4=Kevin N. |year=2024 |title=Hettangian, Early Jurassic coleoids from West Somerset, SW England—filling a gap in the coleoid record of NW Europe |journal=Acta Palaeontologica Polonica |volume=69 |issue=3 |pages=425–445 |doi=10.4202/app.01172.2024 |doi-access=free }} and from Charmouth Mudstone Formation.
Clarkeiteuthis had long phragmocone and ten short, hook-bearing arms. Although it is originally considered as phragmoteuthid, this classification has been discussed by modern researchers, as it lacked a broad three-lobed proostracum (The anterior prolongation of the guard of the phragmocone), the autapomorphy of phragmoteuthid.
C. conocauda had total length about {{cvt|21|cm}}. This species is well preserved, soft tissues such as mantle and ink sac are visible. One arm had around 30 hooks.{{Cite journal |last1=Jenny |first1=Dominique |last2=Fuchs |first2=Dirk |last3=Arkhipkin |first3=Alexander I. |last4=Hauff |first4=Rolf B. |last5=Fritschi |first5=Barbara |last6=Klug |first6=Christian |date=2019-05-28 |title=Predatory behaviour and taphonomy of a Jurassic belemnoid coleoid (Diplobelida, Cephalopoda) |journal=Scientific Reports |language=en |volume=9 |issue=1 |pages=7944 |doi=10.1038/s41598-019-44260-w |pmid=31138838 |pmc=6538661 |issn=2045-2322|doi-access=free |bibcode=2019NatSR...9.7944J }}
Palaeobiology
File:Clarkeiteuthis and Leptolepis reconstruction.png]]
Well-preserved specimens of C. conocauda with Leptolepis bronni (invalid species of Leptolepis{{cite journal |last1=Konwert |first1=M. |last2=Stumpf |first2=S. |date=2017 |title=Exceptionally preserved Leptolepidae (Actinopterygii, Teleostei) from the late Early Jurassic Fossil-Lagerstätten of Grimmen and Dobbertin (Mecklenburg-Western Pomerania, Germany) |journal=Zootaxa |volume=4243 |issue=2 |pages=249–296 |doi=10.11646/zootaxa.4243.2.2|pmid=28610149 }}) in its arms are known from Posidonia Shale. Preservation of fossil and behavior of living cephalopod suggests that Clarkeiteuthis probably contracted its arms to pull prey towards its mouth to cut the spine by using its beaks, and then feed on it. In all the three specimens of C. conocauda with catching preys had Leptolepis in its arms. Leptolepis is most common fish in the formation, and it lacked thick scales, so it was probably the most common prey of Clarkeiteuthis.
Unlike belemnites which are considered as good swimmers, diplobelids like Clarkeiteuthis were probably less active swimmers, with the capability of occasional short bursts of rapid swimming movements.