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Palaeanodonta (bivalve)
Palaeanodonta ("ancient toothless animals") is an extinct clade of stem-pangolins. They were insectivorous ( myrmecophagous), possibly fossorial, and lived from the middle Paleocene to early Oligocene in North America, Europe and Asia. While the taxonomic grouping of Palaeanodonta has been debated,Averianov, A. O. & Lopatin, A. V. (2014."High-level systematics of placental mammals: Current status of the problem."Biology Bulletin, 41(9), 801–816. it is widely thought that they are a sister group to pangolins. Anatomy Skull Palaeanodonts generally have low and caudally-broad skulls, with notable lambdoid crests and inflated bullae and squamosals. Teeth Despite the name of the group and contrary to their pangolin relatives, palaeanodonts are known to have had teeth. Early palaeanodonts retained minimal tribosphenic post-canines while later species had peglike or otherwise reduced molar crowns. Many also had large, characteristic cuspids. Classification and phylogeny ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paleocene
The Paleocene ( ), or Palaeocene, is a geological epoch (geology), epoch that lasted from about 66 to 56 mya (unit), million years ago (mya). It is the first epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name is a combination of the Ancient Greek ''palaiós'' meaning "old" and the Eocene Epoch (which succeeds the Paleocene), translating to "the old part of the Eocene". The epoch is bracketed by two major events in Earth's history. The K–Pg extinction event, brought on by an asteroid impact (Chicxulub impact) and possibly volcanism (Deccan Traps), marked the beginning of the Paleocene and killed off 75% of species, most famously the non-avian dinosaurs. The end of the epoch was marked by the Paleocene–Eocene Thermal Maximum (PETM), which was a major climatic event wherein about 2,500–4,500 gigatons of carbon were released into the atmosphere and ocean systems, causing a spike in global temperatures and ocean acidification. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Squamosal Bone
The squamosal is a skull bone found in most reptiles, amphibians, and birds. In fishes, it is also called the pterotic bone. In most tetrapods, the squamosal and quadratojugal bones form the cheek series of the skull. The bone forms an ancestral component of the dermal roof and is typically thin compared to other skull bones. The squamosal bone lies ventral to the temporal series and otic notch, and is bordered anteriorly by the postorbital. Posteriorly, the squamosal articulates with the quadrate and pterygoid bones. The squamosal is bordered anteroventrally by the jugal and ventrally by the quadratojugal. Function in reptiles In reptiles, the quadrate and articular bones of the skull articulate to form the jaw joint. The squamosal bone lies anterior to the quadrate bone. Anatomy in synapsids Non-mammalian synapsids In non-mammalian synapsids, the jaw is composed of four bony elements and referred to as a quadro-articular jaw because the joint is between the art ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Incertae Sedis
or is a term used for a taxonomy (biology), 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 at specific taxonomic levels is indicated by (of uncertain family), (of uncertain suborder), (of uncertain order) and similar terms. Examples * The fossil plant ''Paradinandra, Paradinandra suecica'' could not be assigned to any family, but was placed ''incertae sedis'' within the order Ericales when described in 2001. * The fossil ''Gluteus minimus (fossil), Gluteus minimus'', described in 1975, could not be assigned to any known animal phylum. The genus is therefore ''incertae sedis'' within the kingdom Animalia. * While it was unclear to which order the New World vultures (family Cathartidae) should be assigned, they were placed in Aves ''incertae sedis''. It was later agreed to place them in a separate order, Cathartiformes. * Boc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metacheiromyidae
Metacheiromyidae ("next to ''Cheiromys''") is an extinct paraphyletic family of myrmecophagous placental mammals within extinct order Palaeanodonta, that lived in North America and Europe from the late Paleocene to middle Eocene.R. M. Schoch (1984."Revision of ''Metacheiromys'' (Wortman, 1903) and a review of the Palaeanodonta."Postilla 192:1-28 Classification and phylogeny Taxonomy * Family: †Metacheiromyidae (paraphyletic family) (Pilgrim, 1932) ** Genus: †'' Brachianodon'' (Gunnell & Gingerich, 1993) *** †''Brachianodon westorum'' (Gunnell & Gingerich, 1993) ** Genus: †'' Mylanodon'' (Secord, 2002) *** †''Mylanodon rosei'' (Secord, 2002) ** Subfamily: † Metacheiromyinae (paraphyletic subfamily) (Wortman, 1903) *** Genus: †'' Metacheiromys'' (Wortman, 1903) **** †''Metacheiromys dasypus'' (Osborn, 1904) **** †''Metacheiromys marshi'' (Wortman, 1903) *** Genus: †'' Palaeanodon'' (Matthew, 1918) **** †''Palaeanodon ignavus'' (Matthew, 1918) **** †''Palaean ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Escavadodon
''Escavadodon'' ("tooth from Escavada") is an extinct genus of pangolin-like myrmecophagous placental mammals of extinct monotypic family Escavadodontidae within extinct order Palaeanodonta, that lived in North America during the middle Paleocene. It contains a single species, ''Escavadodon zygus'', recovered from the Nacimiento Formation of New Mexico. Phylogenetic tree The phylogenetic relationships of genus ''Escavadodon'' is shown in the following cladogram: See also * Mammal classification * Palaeanodonta Palaeanodonta ("ancient toothless animals") is an extinct clade of stem-pangolins. They were insectivorous (Myrmecophagy, myrmecophagous), possibly fossorial, and lived from the middle Paleocene to early Oligocene in North America, Europe and Asi ... References Palaeanodonta Paleocene mammals of North America Torrejonian Fossils of the United States Paleontology in New Mexico Fossil taxa described in 2000 {{Paleo-mammal-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paraphyly
Paraphyly is a taxonomic term describing a grouping that consists of the grouping's last common ancestor and some but not all of its descendant lineages. The grouping is said to be paraphyletic ''with respect to'' the excluded subgroups. In contrast, a monophyletic grouping (a clade) includes a common ancestor and ''all'' of its descendants. The terms are commonly used in phylogenetics (a subfield of biology) and in the tree model of historical linguistics. Paraphyletic groups are identified by a combination of synapomorphies and symplesiomorphies. If many subgroups are missing from the named group, it is said to be polyparaphyletic. The term received currency during the debates of the 1960s and 1970s accompanying the rise of cladistics, having been coined by zoologist Willi Hennig to apply to well-known taxa like Reptilia (reptiles), which is paraphyletic with respect to birds. Reptilia contains the last common ancestor of reptiles and all descendants of that ancest ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
