Justin Lemberg

University of Chicago | UC · Department of Organismal Biology & Anatomy

The origin of quadrupedal locomotion in tetrapods entailed the evolution of a regionalized axial skeleton with sacral ribs. These ribs provide linkage between the pelvis and vertebral column and contribute to body support and propulsion by the hind limb. The closest relatives of limbed vertebrates are not known to possess such a connection and, the...

A fundamental gap in the study of the origin of limbed vertebrates lies in understanding the morphological and functional diversity of their closest relatives. Whereas analyses of the elpistostegalians Panderichthys rhombolepis , Tiktaalik roseae and Elpistostege watsoni have revealed a sequence of changes in locomotor, feeding and respiratory stru...

Significance The water-to-land transition is a major event in vertebrate history, involving significant changes to feeding structures and mechanics. In water, fish often use suction-feeding to capture prey, but this feeding strategy is not possible on land. Therefore, it has been traditionally believed that the invasion of land involved a shift fro...

This document contains supplementary information for - The feeding system of Tiktaalik roseae: an intermediate between suction feeding and biting. This PDF file includes: Figures S1 to S8 Tables S1 to S3 Legends for Movies S1 to S2

Movie S2 | Animation of retrodeformation of the skull of Tiktaalik roseae. Shown are the proposed transformations of cranial elements (in each of the cardinal views), from in situ to in vivo positions. Color coding of anatomical units correspond to those shown in Figs. 2, 3, 4, S6, S7, S8: cheek (green), palate (yellow), skull roof (grey), braincas...

Movie S1 | Animation of cranial kinesis in Tiktaalik roseae. Shown are the proposed rotations of cranial elements (in anterior, posterior, dorsal, and ventral views), from resting to expanded states, due to cranial kinesis. Color coding of anatomical units correspond to those shown in Figs. 2, 3, 4, S6, S7, S8: cheek (green), palate (yellow), skull...

The fin-to-limb transition was marked by the origin of digits and the loss of dermal fin rays. Paleontological research into this transformation has focused on the evolution of the endoskeleton, with little attention paid to fin ray structure and function. To address this knowledge gap, we study the dermal rays of the pectoral fins of 3 key tetrapo...

Video S1. In situ manipulation demonstrating the interconnectedness of the Atractosteus spatula cranial linkage mechanism. A steel wire looped around the anterior tip of the cleithrum and dorsal to the sternohyoideus is used to simulate input of the sternohyoideus and hypaxial muscles in the feeding system of A. spatula. Initially, at resting state...

Video S2. Animation of the Atractosteus spatula feeding mechanism showing anterior-to-posterior expansion of cranial elements throughout the feeding cycle. Initially, the buccal cavity expands as the jaws open and the hyoid remains elevated. This is followed by pharyngeal expansion as the hyoid depresses with the jaws remaining open. Finally, operc...

This document contains supplementary information for - Feeding kinematics and morphology of the alligator gar (Atractosteus spatula , Lacépède, 1803). This PDF file includes: Figures S1 to S12

Living gars are a small clade of seven species that occupy an important position on the actinopterygian phylogenetic tree as members of Holostei, sister‐group to teleosts, and exhibit many plesiomorphic traits used to interpret and reconstruct early osteichthyan feeding mechanisms. Previous studies of gar feeding kinematics have focused on the ram‐...

Modern (lepisosteid) gars are a small clade of seven species and two genera that occupy an important position on the actinopterygian phylogenetic tree as members of the Holostei ( Amia + gars), sister-group of the teleost radiation. Often referred to as “living fossils,” these taxa preserve many plesiomorphic characteristics used to interpret and r...

Understanding the evolutionary transformation of fish fins into tetrapod limbs is a fundamental problem in biology. The search for antecedents of tetrapod digits in fish has remained controversial because the distal skeletons of limbs and fins differ structurally, developmentally, and histologically. Moreover, comparisons of fins with limbs have be...

The functional effects of bone and suture stiffness were considered here using finite element models representing three different theoretical phenotypes of an Alligator mississippiensis mandible. The models were loaded using force estimates derived from muscle architecture in dissected specimens, constrained at the 18th and 19th teeth in the upper...