Mixodectidae
Encyclopedia
Mixodectidae or mixodectids (from Greek μιξο, mixo, "mixed", and δεκτες, dektes "biter") is an extinct family of insectivore
, placental mammals in the order Dermoptera.
The Mixodectids originated in the late Cretaceous
and survived into the Paleocene
in Europe and North America.
. pantolestids
, leptictids
, and palaeoryctids
), preserved dental and cranial anatomies give an idea of mixodectid dietary requirements. Their rodent-like dental pattern was similar to that of the multituberculates
, with a pair of large, strong, and forward-directed incisors and a row of multi-cusped and low-crowned premolars and molars a specialized dental set-up probably used for crushing and opening hard seeds and nuts.
Torrejonian
(Middle Paleocene) Mixodectidae had a dental set-up similar to the oldest Plagiomenids and is therefore supposedly an ancestral (or sister) group of the latter. For many years Elipdophorus, the oldest plagiomenid, was classified as Mixodectidae but was finally regarded as more closely related to plagiomenids in the 1970s based on derived dental resemblances. Though the relation between Mixodectidae and other early placental mammals from the "insectivore-primate transition" remain unclear, clearly a number of the archaic mixodectid dental features seem to foreshadow the more derived conditions of plagiomenids. Furthermore, the postcranial skeleton of Mixodectes shows arboreal specialization similar to those of Plesiadapiformes
and Dermopterans, supporting their inclusion within Euarchonta
.
Insectivora
The order Insectivora is a now-abandoned biological grouping within the class of mammals...
, placental mammals in the order Dermoptera.
The Mixodectids originated in the late Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
and survived into the Paleocene
Paleocene
The Paleocene or Palaeocene, the "early recent", is a geologic epoch that lasted from about . It is the first epoch of the Palaeogene Period in the modern Cenozoic Era...
in Europe and North America.
Description
While there are less anatomical evidence for this group than for other archaic placental families (such as apatemyidsApatemyidae
Apatemyidae is an extinct family of placental mammals that took part in the first placental evolutionary radiation together with other early mammals such as the leptictids....
. pantolestids
Pantolestidae
Pantolestidae is an extinct family of semi-aquatic, placental mammals that took part in the first placental evolutionary radiation together with other early mammals such as the leptictids....
, leptictids
Leptictida
Leptictida is an extinct order of placental mammals. According to cladistic studies, they may be related to Euarchontoglires , although they are more often regarded as the first branch to split from basal eutherians.- Description :The leptictids are a characteristic example of the...
, and palaeoryctids
Palaeoryctidae
Palaeoryctidae is an extinct group of relatively non-specialized placental mammals that strived in North America during the late Cretaceous and took part in the first placental evolutionary radiation together with other early mammals such as the leptictids.- Description :From a near-complete skull...
), preserved dental and cranial anatomies give an idea of mixodectid dietary requirements. Their rodent-like dental pattern was similar to that of the multituberculates
Multituberculata
The Multituberculata were a group of rodent-like mammals that existed for approximately one hundred and twenty million years—the longest fossil history of any mammal lineage—but were eventually outcompeted by rodents, becoming extinct during the early Oligocene. At least 200 species are...
, with a pair of large, strong, and forward-directed incisors and a row of multi-cusped and low-crowned premolars and molars a specialized dental set-up probably used for crushing and opening hard seeds and nuts.
Torrejonian
Torrejonian
The Torrejonian North American Stage on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology , typically set from 63,300,000 to 60,200,000 years BP lasting . It is usually considered to overlap the Selandian and Thanetian within the...
(Middle Paleocene) Mixodectidae had a dental set-up similar to the oldest Plagiomenids and is therefore supposedly an ancestral (or sister) group of the latter. For many years Elipdophorus, the oldest plagiomenid, was classified as Mixodectidae but was finally regarded as more closely related to plagiomenids in the 1970s based on derived dental resemblances. Though the relation between Mixodectidae and other early placental mammals from the "insectivore-primate transition" remain unclear, clearly a number of the archaic mixodectid dental features seem to foreshadow the more derived conditions of plagiomenids. Furthermore, the postcranial skeleton of Mixodectes shows arboreal specialization similar to those of Plesiadapiformes
Plesiadapiformes
Plesiadapiformes is an extinct order of mammals. It is either closely related to the primates or a precursor to them. Many are too derived to be ancestral to primates, but the earliest Plesiadapiformes have teeth that are strongly indicative of a common ancestor...
and Dermopterans, supporting their inclusion within Euarchonta
Euarchonta
The Euarchonta are a grandorder of mammals containing four orders: the Dermoptera or colugos, the Scandentia or treeshrews, the extinct Plesiadapiformes, and the Primates....
.