Kogaionids
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Kogaionidae is a family of fossil mammals within the
extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...
order Multituberculata. Representatives are known from the Upper Cretaceous and the Paleocene of Europe. Having started as island endemics on Hateg Island during the Upper Cretaceous, where they were in fact the dominant mammal group and diverged into rather unique ecological niches, they expanded across Europe in the Paleocene, where they briefly became a major component of its mammal fauna before their extinction.First mammal species identified from the Upper Cretaceous of the Rusca Montana Basin (Transylvania, Romania) Article in Comptes Rendus Palevol https://dx.doi.org/10.1016/j.crpv.2016.04.002 · June 2016 They are considered to be basal members of Cimolodonta.


Classification

This family is part of the
suborder Order ( la, ordo) is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between family and class. In biological classification, the order is a taxonomic rank used in the classification of organisms and ...
Cimolodonta, generally accepted as closely related to Taeniolabidoidea.Thierry Smith, Codrea Vlad, Red Iron-Pigmented Tooth Enamel in a Multituberculate Mammal from the Late Cretaceous Transylvanian " Haţeg Island ", Article in PLoS ONE 10(7):e0132550-1-16 · July 2015 These small multituberculates were named by Rădulescu R. and Samson P. in 1996, who stated they :"Share with Taeniolabidoidea the general shape of the skull, with anterior part of zygomatic arches directed roughly transversely and very short basicranial region, which gives the skull a square-like appearance, but differ from them in having a strongly elongated snout and different dentition," (Kielan-Jaworowska & Hurum 2001, p.418). Recent studies have favoured a position close to Taeniolabidoidea. A 2021 study found them to be the amongst the most basal members of Cimolodonta, more derived only than ''
Bryceomys ''Bryceomys'' is an extinct mammal that lived during the late Cretaceous period (between 100 and 66 million years ago) and thus shared the world with dinosaurs. It was a member of the also extinct order of Multituberculata. It was within the sub ...
'', and they probably originated from an
eobaatarid Eobaataridae is a family of fossil mammals within the order Multituberculata. Remains are known from the Lower Cretaceous of Europe and Asia. They are among the most derived representatives of the informal suborder "Plagiaulacida", and closely re ...
-like ancestor.


Biology

Like some modern
rodents Rodents (from Latin , 'to gnaw') are mammals of the order Rodentia (), which are characterized by a single pair of continuously growing incisors in each of the upper and lower jaws. About 40% of all mammal species are rodents. They are nat ...
and shrews, at least some kogaionids had red, iron-pigmented enamel. In ''
Barbatodon ''Barbatodon'' is a mammal genus from the Upper Cretaceous period. It lived in Transylvania at the same time as some of the last dinosaurs and was a member of the extinct order of Multituberculata. It is within the suborder of Cimolodonta, and t ...
'' this distribution is more similar to that seen in shrews as opposed to the condition seen in rodents, and suggests
insectivore A robber fly eating a hoverfly An insectivore is a carnivorous animal or plant that eats insects. An alternative term is entomophage, which can also refer to the human practice of eating insects. The first vertebrate insectivores wer ...
habits. This is a unique evolutionary route taken in the isolation of their island environment, almost entirely deprived of competing mammals, and inadvertently resulted in their survival across the KT event. In ''
Litovoi tholocephalos ''Litovoi tholocephalos'' is a multituberculate mammal indigenous to Romania Romania ( ; ro, România ) is a country located at the crossroads of Central Europe, Central, Eastern Europe, Eastern, and Southeast Europe, Southeastern Europe ...
'', there was an extreme brain size reduction, displaying one of the smallest brains in proportion to body size of any derived mammal. Additionally, it bore a small dome in its head, like a
pachycephalosaur Pachycephalosauria (; from Greek παχυκεφαλόσαυρος for 'thick headed lizards') is a clade of ornithischian dinosaurs. Along with Ceratopsia, it makes up the clade Marginocephalia. With the exception of two species, most pachyc ...
.


Range

Kogaionids first appear as island endemics on Maastrichtian Romania, then isolated from the rest of Europe. They are in fact the only European multituberculates from the Late Cretaceous, in contrast to the Early Cretaceous' massive multituberculate diversity in Britain and the Iberian Peninsula. A supposed kogaionid is also known from the Campanian of
Appalachia Appalachia () is a cultural region in the Eastern United States that stretches from the Southern Tier of New York State to northern Alabama and Georgia. While the Appalachian Mountains stretch from Belle Isle in Newfoundland and Labrador, Ca ...
, but its identity as a kogaionid is ambiguous and rather unlikely considering the otherwise Hateg Island-restricted range.Paleobiogeographical implications of the fossil mammals from the Maastrichtian of the Hateg Basin Article · January 2002 Perhaps due to their insectivorous habits, kogaionids managed to survive the KT event. During the Paleocene Hateg Island connected to the rest of Europe, and so these multituberculates dispersed; fossils are known in France, Spain and Belgium, beside Romania's Paleocene deposits at Jisou. For a brief period of time these were among the most common mammals in Europe, but by the Late Paleocene the arrival of other multituberculate groups from North America brought a quick decline, culminating in its extinction at the PETM.


References

* Rădulescu and Samson (1996), "The first multituberculate skull from the Late Cretaceous (Maastrichtian) of Europe (Hateg Basin, Romania)". ''Anuarul Institutului de Geologie al României, Supplement 1'' 69, p. 177-178. * 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" Cimolodonta, Cimolomyidae,
Boffiidae ''Boffius'' is a genus of mammal from the Paleocene of Europe, which was named by Vianey-Liaud M. in 1979. It is a member of the extinct order of Multituberculata. Boffius lies within the suborder Cimolodonta and is the only known member of ...
and Kogaionidae, an Internet directory. {{Taxonbar, from=Q6425752 Cimolodonts Cretaceous mammals of Europe Paleogene mammals of Europe Paleocene mammals Maastrichtian first appearances Paleocene extinctions Prehistoric mammal families