condylarthrans

Condylarthra is an extinct order of placental mammals that lived from the Paleocene to the Eocene epochs. The name "Condylarthra" was first proposed by American paleontologist Edward Drinker Cope in 1888, derived from the Greek words "kondylos" (knuckle) and "arthron" (joint), referring to the knuckle-like articulations of their molar teeth. These early ungulate-like mammals were diverse in size and form, ranging from small, shrew-like creatures to larger, herbivorous forms.

Fossil evidence suggests that condylarthrans occupied a variety of ecological niches, with some being omnivores or carnivores, while others were primarily herbivores. Their dentition, characterized by bunodont or selenodont molars, indicates adaptations for grinding plant matter. The skeletal structure of condylarthrans shows primitive features that link them to early ungulate evolution, although their exact phylogenetic position within placental mammals has been a subject of ongoing debate and revision.

Historically, condylarthrans were considered a direct ancestral group to modern ungulates (hoofed mammals), including perissodactyls (odd-toed ungulates like horses and rhinoceroses) and artiodactyls (even-toed ungulates like deer and cattle). However, more recent molecular and morphological studies have led to a re-evaluation of these relationships. Many groups previously classified as condylarthrans are now placed within other mammalian orders, or are considered extinct side branches. Despite these taxonomic changes, the study of condylarthrans remains crucial for understanding the early diversification and evolution of placental mammals, particularly in the post-Cretaceous world.