Paleocene extinctions

Ammonoids are extinct, typically coiled-shelled cephalopods composing the subclass Ammonoidea. They are more closely related to living octopuses, squid, and cuttlefish (which compose the clade Coleoidea) than they are to nautiluses (family Nautilidae), which they resemble. The earliest ammonoids appeared during the Emsian stage of the Early Devonian, around 410-408 million years ago, with the last species vanishing during or soon after the Cretaceous–Paleogene extinction event approximately 66 million years ago. They are often called ammonites, which is most frequently used for members of the

Ammonitida, or true ammonites, are an order of ammonoid cephalopods that lived from the Jurassic through Paleocene time periods, commonly with intricate ammonitic sutures.

Ichthyodectiformes is an extinct order of marine stem-teleost ray-finned fish. The order is named after the genus Ichthyodectes, established by Edward Drinker Cope in 1870. Ichthyodectiforms are usually considered to be some of the closest relatives of the teleost crown group.

Thoracosaurus (chest lizard) is an extinct genus of long-snouted eusuchian which existed during the Late Cretaceous and Early Paleocene in North America and Europe.

Periptychidae is a family of Cretaceous–Paleocene placental mammals, known definitively only from North America. The family is part of a radiation of early herbivorous and omnivorous mammals formerly classified in the extinct order "Condylarthra", which may be related to some or all living ungulates (hoofed mammals). Periptychids are distinguished from other "condylarths" by their teeth, which have swollen premolars and unusual vertical enamel ridges. The family includes both large and small genera, with the larger forms having robust skeletons. Known skeletons of periptychids suggest generali

The Ancyloceratina were a diverse suborder of ammonite most closely related to the ammonites of order Lytoceratina. They evolved during the Late Jurassic but were not very common until the Cretaceous period, when they rapidly diversified and became one of the most distinctive components of Cretaceous marine faunas. They have been recorded from every continent and many are used as zonal or index fossils. The most distinctive feature of the majority of the Ancyloceratina is the tendency for most of them to have shells that are not regular spirals like most other ammonites. These irregularly-coil

Taeniolabidoidea is a group of extinct mammals known whose fossils can be found in North America and Asia. They were the largest members of the extinct order Multituberculata, as well as the largest non-therian mammals. Lambdopsalis even provides direct fossil evidence of mammalian fur in a fairly good state of preservation for a 60-million-year-old animal. Some of these animals were large for their time; Taeniolabis taoensis is the largest known multituberculate and though smaller, Yubaatar is the largest known Mesozoic Asian multituberculate. T. taoensis averaged a body mass of .

Deltatheroida is an extinct group of basal metatherians that were distantly related to modern marsupials. The majority of known members of the group lived in the Cretaceous; one species, Gurbanodelta kara, is known from the late Paleocene (Gashatan) of China. Their fossils are restricted to Central Asia and North America. This order can be defined as all metatherians closer to Deltatheridium than to Marsupialia.

Ptilodontidae is a family of primitive mammals within the extinct order Multituberculata. Representatives are known from the Upper Cretaceous and Paleocene of North America.

Mixodectidae, from Ancient Greek μιξο (mixo) "mixed", and δεκτες (dektes) "biter", is an extinct family of insectivorous placental mammals in the order Dermoptera. The mixodectids originated in the late Cretaceous and survived into the Paleocene in Europe and North America.

Bemalambda (meaning "stepped lambda") is a genus of extinct mammal, belonging to the pantodonts. It lived in the lower-middle Paleocene (about 63–58 million years ago) and the fossil remains have been found in China.

Kogaionidae is a family of fossil mammals within the extinct order Multituberculata. Representatives are known from the Upper Cretaceous and the Paleocene of Europe. Having started as island endemics on Hațeg 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. They are considered to be basal members of Cimolodonta.

Bemalambdidae is an extinct family of pantodont mammals known from Early and Middle Paleocene of China.

Cimolodontidae is a family of fossil mammals within the extinct order Multituberculata. Representatives are known from the Upper Cretaceous and Paleocene of North America. The family Cimolodontidae was named by Othniel Charles Marsh in 1889 and is part of the suborder Cimolodonta within the superfamily Ptilodontoidea.

Baculitidae is a family of extinct ammonoid cephalopods that lived mostly during the Late Cretaceous, and often included in the suborder Ancyloceratina.

Taeniolabididae is one of the two multituberculate clades within Taeniolabidoidea. Originally basically synonymous with Taeniolabidoidea, it has more recently been found to be a specific clade including Kimbetopsalis, Taeniolabis and some former members of the Catopsalis wastebasket taxon, as opposed to Lambdopsalidae, which includes most other genera outside of Valenopsalis and possibly Bubodens, both of which more basal taxa.