Scrotifera ("beasts with scrotum") is a

clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...

placental mammals Placental mammals (infraclass Placentalia ) are one of the three extant subdivisions of the class Mammalia, the other two being Monotremata and Marsupialia. Placentalia contains the vast majority of extant mammals, which are partly distinguishe ...

that groups together grandorder

Ferungulata Ferungulata ("wild beasts and ungulates") is a grandorder of placental mammals that groups together mirorder Ferae and clade Pan-Euungulata. It has existed in two guises, a traditional one based on morphological analysis and a revised one taking ...

, clade Apo-Chiroptera (aka order

Chiroptera Bats are mammals of the Order (biology), order Chiroptera.''cheir'', "hand" and πτερόν''pteron'', "wing". With their forelimbs adapted as wings, they are the only mammals capable of true and sustained flight. Bats are more agile in fli ...

), other extinct members and their common ancestors. The clade Scrotifera is a sister group to the order

Eulipotyphla Eulipotyphla (, which means "truly fat and blind") is an order of mammals suggested by molecular methods of phylogenetic reconstruction, which includes the laurasiatherian members of the now-invalid polyphyletic order Lipotyphla, but not the afr ...

(true insectivores) based on evidence from

molecular phylogenetics Molecular phylogenetics () is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominantly in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to ...

, and together they make superorder

Laurasiatheria Laurasiatheria ("laurasian beasts") is a superorder of placental mammals that groups together true insectivores ( eulipotyphlans), bats ( chiropterans), carnivorans, pangolins ( pholidotes), even-toed ungulates (artiodactyls), odd-toed ungulates ...

. The

last common ancestor In biology and genetic genealogy, the most recent common ancestor (MRCA), also known as the last common ancestor (LCA) or concestor, of a set of organisms is the most recent individual from which all the organisms of the set are descended. The ...

of Scrotifera is supposed to have diversified ca. 73.1 to 85.5 million years ago.

Etymology

Peter Waddell, then of the

Institute of Statistical Mathematics An institute is an organisational body created for a certain purpose. They are often research organisations (research institutes) created to do research on specific topics, or can also be a professional body. In some countries, institutes can ...

, explains the etymology of the clade's name as follows:

The name comes from the word ''
scrotum The scrotum or scrotal sac is an anatomical male reproductive structure located at the base of the penis that consists of a suspended dual-chambered sac of skin and smooth muscle. It is present in most terrestrial male mammals. The scrotum cont ...
'', a pouch in which the
testes A testicle or testis (plural testes) is the male reproductive gland or gonad in all bilaterians, including humans. It is homologous to the female ovary. The functions of the testes are to produce both sperm and androgens, primarily testoster ...
permanently reside in the adult male. All members of the group have a postpenile scrotum, often prominently displayed, except for some aquatic forms and
pangolin Pangolins, sometimes known as scaly anteaters, are mammals of the order Pholidota (, from Ancient Greek ϕολιδωτός – "clad in scales"). The one extant family, the Manidae, has three genera: '' Manis'', '' Phataginus'', and '' Smut ...
(which has the testes just below the skin). It appears to be an ancestral character for this group, yet other orders generally lack this as an ancestral feature, with the probable exception of
Primate Primates are a diverse order of mammals. They are divided into the strepsirrhines, which include the lemurs, galagos, and lorisids, and the haplorhines, which include the tarsiers and the simians (monkeys and apes, the latter including huma ...
s.

Classification and phylogeny

History of phylogeny

In year

2006 File:2006 Events Collage V1.png, From top left, clockwise: The 2006 Winter Olympics open in Turin; Twitter is founded and launched by Jack Dorsey; The Nintendo Wii is released; Montenegro 2006 Montenegrin independence referendum, votes to declare ...

clade

Pegasoferae Pegasoferae ("winged beast") is a proposed clade of mammals based on genomic research in molecular systematics by Nishihara, Hasegawa and Okada (2006). To the surprise of the authors, their data led them to propose a clade that includes bats (or ...

(a clade of mammals that includes orders Chiroptera,

Carnivora Carnivora is a Clade, monophyletic order of Placentalia, placental mammals consisting of the most recent common ancestor of all felidae, cat-like and canidae, dog-like animals, and all descendants of that ancestor. Members of this group are f ...

, Perissodactyla and

Pholidota Pangolins, sometimes known as scaly anteaters, are mammals of the order Pholidota (, from Ancient Greek ϕολιδωτός – "clad in scales"). The one extant family, the Manidae, has three genera: '' Manis'', ''Phataginus'', and ''Smutsia ...

) was proposed as part of clade Scrotifera and sister group to the order

Artiodactyla The even-toed ungulates (Artiodactyla , ) are ungulates—hoofed animals—which bear weight equally on two (an even number) of their five toes: the third and fourth. The other three toes are either present, absent, vestigial, or pointing poster ...

, based on genomic research in molecular systematics. The monophyly of the group is not well supported, and recent studies have indicated that this clade is not a natural grouping. According to 2022 study of Matthew F. Jones, Nancy Simmons and K. Christopher Beard, two nyctitheres species ('' Eosoricodon terrigena'' and '' "Wyonycteris" microtis'') were identified to be most closely related to bats.Matthew F. Jones, Nancy Simmons, K. Christopher Beard (2022.) "Relationship of nyctitheres (Mammalia, Nyctitheriidae) to bats and other laurasiatherians", in
"The Society of Vertebrate Paleontology 82nd annual meeting"
'

Taxonomy

* ''Clade'': Scrotifera ** Grandorder:

** ''Clade'': Apo-Chiroptera (bats) *** Order:

(bats) ** Family: † Eosoricodontidae ** ''

Incertae sedis ' () or ''problematica'' is a term used for a taxonomic group where its broader relationships are unknown or undefined. Alternatively, such groups are frequently referred to as "enigmatic taxa". In the system of open nomenclature, uncertainty ...

'': *** †'' "Wyonycteris" microtis''

Phylogeny

The phylogenetic relationships of clade Scrotifera are shown in the following cladogram, reconstructed from mitochondrial and nuclear DNA and protein characters, as well as the fossil record:Peter J. Waddell, Hirohisa Kishino, Rissa Ota (2001.
"A Phylogenetic Foundation for Comparative Mammalian Genomics"
Genome Informatics 12: 141–154O’Leary, M. A., Bloch JI, Flynn, J. J., Gaudin, T. J., Giallombardo, A., Giannini, N. P., Goldber, S. L, Kraatz, B. P., Luo, Z-X, Jin Meng, Xijun Ni, Novacek, M. J., Perini, F. A., Randall, Z. S., Rougier, G. W., Sargis, E. J., Silcox, M. T., Simmons, N. B., Spaulding, M. Velazco, P. M., Weksler, M., Wible, J. R. Cirranello, A. L. (2013.
"The Placental Mammal Ancestor and the Post–K-Pg Radiation of Placentals."
Science 339:6120:662-667.Frank Zachos (2020.
"Mammalian Phylogenetics: A Short Overview of Recent Advances"
In book: "Mammals of Europe – Past, Present, and Future" (pp.31-48)Xue Lv, Jingyang Hu, Yiwen Hu, Yitian Li, Dongming Xu, Oliver A. Ryder, David M. Irwin, Li Yu (2021.
"Diverse phylogenomic datasets uncover a concordant scenario of laurasiatherian interordinal relationships"
Molecular Phylogenetics and Evolution, Volume 157

References

Mammal taxonomy {{mammal-stub