Original paper
The postcranial ontogeny of Dysalotosaurus lettowvorbecki (Ornithischia: Iguanodontia) and implications for the evolution of ornithopod dinosaurs
Hübner, Tom
Palaeontographica Abteilung A Band 310 Lieferung 3-6 (2018), p. 43 - 120
172 references
published: May 30, 2018
Abstract
Ornithopoda is a diverse clade of ornithischian dinosaurs, which superficially shows a conservative postcranial bauplan. A closer look, however, reveals many morphological changes during their evolution which often reflect adaptations towards larger and heavier bodies, as well as towards more graviportal and, at least facultative, quadrupedal locomotion. To study the pattern and distribution of these changes, analysis of the ontogeny of a well-preserved taxon, which ideally represents an intermediate stage of both body size and phylogenetic position, is crucial. Dysalotosaurus, a basal iguanodontian ornithopod, is known from numerous well preserved skeletal elements of different ontogenetic stages and is here used as a model taxon. Although somatically mature individuals of Dysalotosaurus are not known, a combination of qualitative and quantitative methods reveals several aspects of its ontogeny, such as precocial breeding behavior, the posterior-to-anterior sequence of neurocentral suture closure, and the increasing robustness of many parts of the skeleton. Additionally, the ontogeny of Dysalotosaurus also demonstrates that morphological changes in the ornithopod postcranium were influenced by a mosaic of different heterochronic processes taking place even within single skeletal elements with changing relative intensity and developmental sequence.
Keywords
Ornithopoda • ontogeny • allometry • heterochrony • evolution