Condylarth

Condylarth is a term that has been used in paleontology to refer to an extinct group of placental mammals. The name "Condylarthra" literally means "knuckle-jointed" and was coined by the paleontologist Henry Fairfield Osborn in 1888. This group was proposed to encompass a diverse array of early ungulates and their relatives, characterized by the presence of primitive, generalized molar teeth with cusps that were often arranged in crescentic or bunodont patterns.

Historically, condylarths were considered to be a basal offshoot within Placentalia, potentially ancestral to modern hoofed mammals such as perissodactyls (horses, rhinoceroses) and artiodactyls (even-toed ungulates like deer and cattle). They were thought to have originated in the Late Cretaceous or early Paleocene epochs and diversified throughout the Cenozoic Era. Fossil evidence suggested a wide geographical distribution, with remains found on several continents.

However, the concept of Condylarthra as a unified, monophyletic group has been largely abandoned by modern paleontologists. Phylogenetic analyses, particularly those incorporating molecular data and a broader range of fossil taxa, have indicated that the traits used to define condylarths, such as generalized molar morphology, are likely plesiomorphic (ancestral) and do not necessarily indicate close evolutionary relationships. Instead, the taxa previously assigned to Condylarthra are now generally dispersed among various, more narrowly defined mammalian orders, often placed within the superorder Laurasiatheria. While the term "condylarth" is rarely used in contemporary systematic literature, it remains a significant historical concept in understanding the early evolution of mammals.