''Hahnodon'' ("Hahn's tooth") is an

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

mammaliaform Mammaliaformes ("mammalian forms") is a clade of synapsid tetrapods that includes the crown group mammals and their closest extinct relatives; the group radiated from earlier probainognathian cynodonts during the Late Triassic. It is defined a ...

s from the Early

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...

Ksar Metlili Formation The Ksar Metlili Formation is a geological formation in eastern High Atlas of Morocco, it is late Tithonian to Berriasian in age. It is approximately thick and primarily consists of mudstone and sandstone, with thin calcareous beds. One of these ...

in Morocco. Although originally considered to be a relatively early member of the extinct clade

Multituberculata Multituberculata (commonly known as multituberculates, named for the multiple tubercles of their teeth) is an extinct Order (biology), order of rodent-like mammals with a fossil record spanning over 130 million years. They first appeared in the M ...

, recent studies indicate that it instead is a

haramiyid Haramiyida is a possibly paraphyletic order of mammaliaform cynodonts or mammals of controversial taxonomic affinites. Their teeth, which are by far the most common remains, resemble those of the multituberculates. However, based on ''Haramiyavia ...

Fossils and distribution

''Hahnodon taqueti'' is based on a single lower molar found in Lower Cretaceous

strata In geology and related fields, a stratum (: strata) is a layer of Rock (geology), rock or sediment characterized by certain Lithology, lithologic properties or attributes that distinguish it from adjacent layers from which it is separated by v ...

Morocco Morocco, officially the Kingdom of Morocco, is a country in the Maghreb region of North Africa. It has coastlines on the Mediterranean Sea to the north and the Atlantic Ocean to the west, and has land borders with Algeria to Algeria–Morocc ...

Classification

Denise Sigogneau-Russell Denise Sigogneau-Russell (born ''c.'' 1941/42) is a French palaeontologist who specialises in mammals from the Mesozoic, particularly from France and the UK. She is currently based at the Muséum National d'Histoire Naturelle. Background Denise S ...

(1991) classified ''Hahnodon'' as a member of Multituberculata, but others later considered it to be related to members of Haramiyida. The description of ''

Cifelliodon ''Cifelliodon'' is an extinct genus of mammaliaforms from the Lower Cretaceous of North America. In the describing paper, it was considered one of the latest surviving haramiyids yet known, belonging to the family Hahnodontidae. Its discovery l ...

'' from North America confirmed that ''Hahnodon'' — and by extension, Hahnodontidae — belong to Haramiyida.Adam K. Huttenlocker; David M. Grossnickle; James I. Kirkland; Julia A. Schultz; Zhe-Xi Luo (2018). "Late-surviving stem mammal links the lowermost Cretaceous of North America and Gondwana". Nature. in press. doi:10.1038/s41586-018-0126-y.

References

Bibliography

* Sigogneau-Russell (1991), "First evidence of

(Mammalia) in the Mesozoic of Africa". Neues Jahrb Geol Paläontol, Monatshefte, p. 119-125. * Kielan-Jaworowska Z & Hurum JH (2001), "Phylogeny and Systematics of multituberculate mammals". ''Paleontology'' 44, p. 389-429. * Much of this information has been derived fro

MESOZOIC MAMMALS: Basal Multituberculata, an Internet directory. {{Taxonbar, from1=Q18578265, from2=Q944805 Haramiyida Berriasian life Early Cretaceous synapsids of Africa Cretaceous Morocco Fossils of Morocco Fossil taxa described in 1991 Taxa named by Denise Sigogneau-Russell