Print ISSN: 0031-0247
Online ISSN: 2274-0333
A femur of the giant bird Gargantuavis
Les traces de pas d'amphibiens, de dinosaures et autres reptiles du Mesozoïque Français
La palichnofaune de vertébrés tétrapodes du permien supérieur du Bassin de Lodève .
Fossil vertebrate assemblage at Las Aguilas
About the genus Propachynolophus Lemoine 1891
Origins of avian reproduction: answers and questionsfrom dinosaurs.Avian reproduction; clutch; dinosaurs; egg size; nests; oviducts; parental care
The reproductive biology of living birds differs dramatically from that of other extant vertebrates. Distinctive features common to most birds include a single ovary and oviduct, production of one egg at daily or greater intervals, incubation by brooding and extensive parental care. The prevalence of male parental care is most exceptional among living amniotes. A variety of hypotheses exist to explain the origin of avian reproduction. Central to these models are proposed transitions from a condition of no care to maternal, paternal or biparental care systems. These evolutionary models incorporate a number of features potentially preservable or inferable from the fossil record (integument, skeletal adaptations for flight, egg and clutch size, nest form, hatchling developmental stage, the number and function of oviducts, and the mode of egg incubation). Increasing availability of data on dinosaur reproduction provides a means of assessing these hypotheses with fossil evidence. We compare dinosaur data to a selection of models that emphasize maternal, paternal or biparental care. Despite some congruence with dinosaur features, no single model on the evolution of avian reproduction conforms fully to the fossil record, and the ancestral parental care system of birds remains ambiguous. Further investigation into dinosaur parental care, nest structures, clutch geometry, egg-pairing, eggshell porosity, and embryo identification may eventually resolve these issues.
Published in Vol. 32, Fasc. 2-4 (2003)