Bone abnormalities are common in theropod dinosaur skeletons, but before now no specimen was know... more Bone abnormalities are common in theropod dinosaur skeletons, but before now no specimen was known with more than four afflicted bones of the pectoral girdle and/or forelimb. Here we describe the pathology of a specimen of the theropod dinosaur Dilophosaurus wetherilli with eight afflicted bones of the pectoral girdle and forelimb. On its left side the animal has a fractured scapula and radius and large fibriscesses in the ulna and the proximal thumb phalanx. On its right side the animal has abnormal torsion of the humeral shaft, bony tumors on the radius, a truncated distal articular surface of metacarpal III, and angular deformities of the first phalanx of the third finger. Healing and remodeling indicates that the animal survived for months and possibly years after its ailments began, but its right third finger was permanently deformed and lacked the capability of flexion. The deformities of the humerus and the right third finger may be due to developmental osteodysplasia, a condition known in extant birds but unreported in non-avian dinosaurs before now.
In the Mammalia, vestigial skeletal structures abound but have not previously been the focus of s... more In the Mammalia, vestigial skeletal structures abound but have not previously been the focus of study, with a few exceptions (e.g., whale pelves). Here we use a phylogenetic bracketing approach to identify vestigial structures in mammalian postcranial skeletons and present a descriptive survey of such structures in the Mammalia. We also correct previous misidentifications, including the previous misidentification of vestigial caviid metatarsals as sesamoids. We also examine the phylogenetic distribution of vestigiality and loss. This distribution indicates multiple vestigialization and loss events in mammalian skeletal structures, especially in the hand and foot, and reveals no correlation in such events between mammalian fore and hind limbs.
The inclination of the scapular blade and the resting pose of the forelimb in dinosaurs differ am... more The inclination of the scapular blade and the resting pose of the forelimb in dinosaurs differ among reconstructions and among skeletal mounts. For most dinosaurian taxa, no attempt has previously been made to quantify the correct resting positions of these elements. Here, we used data from skeletons preserved in articulation to quantify the resting orientations of the scapula and forelimb in dinosaurs. Specimens were included in the study only if they were preserved lying on their sides; for each specimen the angle between forelimb bones at a given joint was included in the analysis only if the joint was preserved in articulation. Using correlation analyses of the angles between the long axis of the sacrum, the first dorsal centrum, and the scapular blade in theropods and Eoraptor, we found that vertebral hyperextension does not influence scapular orientation in saurischians. Among examined taxa, the long axis of the scapular blade was found to be most horizontal in bipedal saurisc...
... Lack of precise fit between the humeral head and the glenoid suggests that there was muchcart... more ... Lack of precise fit between the humeral head and the glenoid suggests that there was muchcartilage padding in the joint, as in extant archosaurs (Holliday et al., 2001; P. Senter, pers. obs.). ... 1 Allosaurus fragilis DINO 11541 l 85o Chure, 2001: fig. 1 ...
... 2000), and that the fossil bird Confuciusornis sanctus lacked os-sified uncinate processes (H... more ... 2000), and that the fossil bird Confuciusornis sanctus lacked os-sified uncinate processes (Hou et ... How-ever, these dental differences can be attributed to ontogeny, as ontoge-netic reduction in dental recurvature (especially in posterior teeth) and ontogenetic decrease in ...
Bone abnormalities are common in theropod dinosaur skeletons, but before now no specimen was know... more Bone abnormalities are common in theropod dinosaur skeletons, but before now no specimen was known with more than four afflicted bones of the pectoral girdle and/or forelimb. Here we describe the pathology of a specimen of the theropod dinosaur Dilophosaurus wetherilli with eight afflicted bones of the pectoral girdle and forelimb. On its left side the animal has a fractured scapula and radius and large fibriscesses in the ulna and the proximal thumb phalanx. On its right side the animal has abnormal torsion of the humeral shaft, bony tumors on the radius, a truncated distal articular surface of metacarpal III, and angular deformities of the first phalanx of the third finger. Healing and remodeling indicates that the animal survived for months and possibly years after its ailments began, but its right third finger was permanently deformed and lacked the capability of flexion. The deformities of the humerus and the right third finger may be due to developmental osteodysplasia, a condition known in extant birds but unreported in non-avian dinosaurs before now.
In the Mammalia, vestigial skeletal structures abound but have not previously been the focus of s... more In the Mammalia, vestigial skeletal structures abound but have not previously been the focus of study, with a few exceptions (e.g., whale pelves). Here we use a phylogenetic bracketing approach to identify vestigial structures in mammalian postcranial skeletons and present a descriptive survey of such structures in the Mammalia. We also correct previous misidentifications, including the previous misidentification of vestigial caviid metatarsals as sesamoids. We also examine the phylogenetic distribution of vestigiality and loss. This distribution indicates multiple vestigialization and loss events in mammalian skeletal structures, especially in the hand and foot, and reveals no correlation in such events between mammalian fore and hind limbs.
The inclination of the scapular blade and the resting pose of the forelimb in dinosaurs differ am... more The inclination of the scapular blade and the resting pose of the forelimb in dinosaurs differ among reconstructions and among skeletal mounts. For most dinosaurian taxa, no attempt has previously been made to quantify the correct resting positions of these elements. Here, we used data from skeletons preserved in articulation to quantify the resting orientations of the scapula and forelimb in dinosaurs. Specimens were included in the study only if they were preserved lying on their sides; for each specimen the angle between forelimb bones at a given joint was included in the analysis only if the joint was preserved in articulation. Using correlation analyses of the angles between the long axis of the sacrum, the first dorsal centrum, and the scapular blade in theropods and Eoraptor, we found that vertebral hyperextension does not influence scapular orientation in saurischians. Among examined taxa, the long axis of the scapular blade was found to be most horizontal in bipedal saurisc...
... Lack of precise fit between the humeral head and the glenoid suggests that there was muchcart... more ... Lack of precise fit between the humeral head and the glenoid suggests that there was muchcartilage padding in the joint, as in extant archosaurs (Holliday et al., 2001; P. Senter, pers. obs.). ... 1 Allosaurus fragilis DINO 11541 l 85o Chure, 2001: fig. 1 ...
... 2000), and that the fossil bird Confuciusornis sanctus lacked os-sified uncinate processes (H... more ... 2000), and that the fossil bird Confuciusornis sanctus lacked os-sified uncinate processes (Hou et ... How-ever, these dental differences can be attributed to ontogeny, as ontoge-netic reduction in dental recurvature (especially in posterior teeth) and ontogenetic decrease in ...
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