The noncervical lateral transverse foramina.

The lateral vertebral foramen (LVF) is an osseous feature found in thoracic and lumbar vertebrae of some artiodactyls and perissodactyls. To learn more about the distribution and characteristics of the LVF, we examined museum specimens from the Smithsonian mammal collection and teaching specimens from the Cornell University College of Veterinary Medicine. We identified five anatomically different types of LVF and noted their occurrence in 60 species. The LVF varies from a deep lateral groove at the cranial intervertebral notch, to as many as three distinct foramina located bilaterally in the caudal half of each vertebra. A nomenclature was developed to describe these five distinctly different LVF forms. The interspecific distribution of the LVF varies from examples such as the gazelle Gazella spekei, where the LVF occurs only in the thoracic region, to others such as the Siberian musk deer Moschus berezovski, where the LVF is predominant only in the lumbar region. Others, such as the Bos (cows), have large LVF along most of both the thoracic and lumbar regions of the vertebral column. Some did not have any form of LVF, such as the Giraffidae (giraffes) and Cetacea (whales). No LVF were found in 15 species representing nine families of the outgroup Carnivora, thus the LVF appears to be a characteristic specific to the artiodactyls and perissodactyls.