Int. J. Dev. Biol. 58: 935 - 948 (2014)

https://doi.org/10.1387/ijdb.150087db

Vol 58, Issue 10-11-12

Special Issue: Developmental Herpetology

Evolution of viviparous reproduction in Paleozoic and Mesozoic reptiles

Published: 2 July 2015

Daniel G. Blackburn*^,1 and Christian A. Sidor²

¹Department of Biology and Electron Microscopy Center, Trinity College, Hartford, CT and ²Department of Biology and Burke Museum, University of Washington, Seattle, WA, USA

Abstract

Although viviparity (live-bearing reproduction) is widely distributed among lizards and snakes, it is entirely absent from other extant Reptilia and many extinct forms. However, paleontological evidence reveals that viviparity was present in at least nine nominal groups of pre-Cenozoic reptiles, representing a minimum of six separate evolutionary origins of this reproductive mode. Two viviparous clades (sauropterygians and ichthyopterygians) lasted more than 155 million years, a figure that rivals the duration of mammalian viviparity. Circumstantial evidence indicates that extinct viviparous reptiles had internal fertilization, amniotic fetal membranes, and placentas that sustained developing embryos via provision of respiratory gases, water, calcium, and possibly organic nutrients. Production of offspring via viviparity facilitated the invasion of marine habitats in at least five reptilian lineages. Thus, this pattern of embryonic development and reproduction was central to the ecology and evolution of these ancient animals, much as it is to numerous extant species of vertebrates.

Keywords

viviparity, reproductive patterns, paleontology, placentas