Justin Georgi

Midwestern University · Department of Anatomy at the AZCOM

Mastectomy remains a major treatment for breast cancers and prophylaxis for carriers of the BRCA genes, yet the amount of tissue removed is variable across surgical approaches. The anatomical and surgical literatures provide conflicting and incomplete descriptions of breast gross anatomy. In order to clarify this anatomy, we dissected 6 male and 15...

The gerenuk (Litocranius walleri) is an African ruminant that feeds on high growing foliage by standing erect on its hindlimbs and extending its long neck. We hypothesize that extensive myological adaptation would be present in the muscles that facilitate head stability and movement, as well as muscles that anchor the neck. The vertebral musculatur...

Requiring both wing-propelled swimming and rugged overland locomotion, Macaroni penguins possess highly specialized morphology in both limbs. We dissected both the wing and hindlimb of one female and one male macaroni penguin. The distal wing exhibits very reduced musculature, and only retains very small brachialis and dorsal ulno-metacarpal muscle...

Revealing behavioral secrets in extinct species Extinct species had complex behaviors, just like modern species, but fossils generally reveal little of these details. New approaches that allow for the study of structures that relate directly to behavior are greatly improving our understanding of the lifestyles of extinct animals (see the Perspectiv...

Stylemys nebrascensis is a testudinid tortoise from North America that lived in subtropical areas during the Paleogene, being one of the anatomically best-known species within extinct turtles. The specimen at the Raymond M. Alf Museum (USA), RAM 8315, corresponds to an almost complete skull with articulated jaws, which were virtually removed — toge...

Neuroanatomical reconstructions of extinct animals have long been recognized as powerful proxies for palaeoecology, yet our understanding of the endocranial anatomy of dromaeosaur theropod dinosaurs is still incomplete. Here, we used X-ray computed microtomography (µCT) to reconstruct and describe the endocranial anatomy, including the endosseous l...

Ontogenetic changes in the musculoskeletal system, ecological niche, and feeding habits of the American alligator ( Alligator mississippiensis ) have all been hypothesized to relate to similar ontogenetic shifts in locomotion. Anecdotal evidence of the loss of galloping in some crocodilian taxa lends some support to this hypothesis. This study repr...

Several studies have looked at muscular strength in the jaws of crocodilians but there are little published data that examine the direct measurement of muscular strength in the limbs of crocodilians. When an Alligator mississippiensis was surrendered to the Phoenix Herpetological Society (PHS) with clear physical deficits, such as malnutrition and...

The tail has many functions for an American Alligator ( Alligator mississippiensis ). Previous research demonstrates that adding a prosthetic tail to a tailless alligator improves locomotor performance and restores posture. We experimented on the effects of prosthesis parameters on the kinematics and behavior of an American Alligator whose tail has...

Turtles are one of the least explored clades of reptiles with respect to palaeoneuroanatomy. Few detailed descriptions of endocranial features such as the brain morphology or inner ear exist for extant and extinct forms. In this contribution , we present the first CT-based reconstructions of endocranial morphology (brain and inner ear) and the nasa...

Turtles are one of the least explored clades of reptiles regarding paleoneuroanatomy. Here we describe the endocranial morphology of the extinct terrestrial horned meiolaniid turtles Niolamia argentina and Gaffneylania auricularis from Patagonia, and Meiolania platyceps from Australia, along with six terrestrial testudinid species, using CT scans....

The aim of this research is to describe the changes of head and neck kinematics as they relate to the growth of the African spurred tortoise ( Geochelone sulcata ). The basics of tortoise locomotion have been described previously. These studies, however, have not investigated locomotor changes in head kinematics due to body size. Infra‐red motion c...

Previous investigations have correlated vestibular function to locomotion in vertebrates by scaling semicircular duct radius of curvature to body mass. However, this method fails to discriminate bipedal from quadrupedal non-avian dinosaurs. Because they exhibit a broad range of relative head sizes, we use dinosaurs to test the hypothesis that semic...

Specimens and measurements used in this study. All Skull length and Body length values and all Body mass values except for the four taxa listed in Table S2 are taken from the listed references. (DOCX)

Femur measurements used to calculate body mass estimates in four specimens without reliable literature values. Diameter and length for Masiakasaurus knopfleri are composite values from the six specimens listed in Carano et al. (2002, J Vert Paleo 22:510-534) with femur lengths greater than 170 mm (8). (DOCX)

Simosuchus clarki Buckley, Brochu, Krause, and Pol, 200010. Buckley , G. A. , Brochu , C. A. , Krause , D. W. and Pol , D. 2000. A pug-nosed crocodyliform from the Late Cretaceous of Madagascar. Nature, 405: 941–944. [CrossRef], [PubMed], [Web of Science ®], [CSA]View all references, a small, pug-nosed notosuchian crocodyliform from the Late Cr...

Simosuchus clarki is a small, pug-nosed notosuchian crocodyliform from the Late Cretaceous of Madagascar. Originally described on the basis of a single specimen including a remarkably complete and well-preserved skull and lower jaw, S. clarki is now known from five additional specimens that preserve portions of the craniofacial skeleton. Collective...

Mammals chew more rhythmically than lepidosaurs. The research presented here evaluated possible reasons for this difference in relation to differences between lepidosaurs and mammals in sensorimotor systems. Variance in the absolute and relative durations of the phases of the gape cycle was calculated from kinematic data from four species of primat...

This chapter discusses the structure of the inner ear of aquatic reptiles and birds and their variations in morphology and functional responses. It examines the anatomy and function of semicircular canals and investigates the evolutionary changes of canal shape in response to the reinvasion of aquatic environments by turtles, varanoids, crocodilian...

YPM 13525 lacks an ossified bulla. It has a mediolaterally broad basioccipital, a large entoglenoid process, and a deeply incised glaserian fissure of the squamosal, caudal and rostral tympanic processes on the petrosal, a foramen for an internal carotid artery (ICA) that entered the tympanic cavity from a posteromedial position, bony tubes enclosi...

Computed tomography (CT) scanning and subsequent coarse digital preparation of jacketed material from the Cretaceous and Paleogene of Madagascar conducted at Stony Brook University has greatly augmented mechanical preparation objectives, Prepreparation scanning allows prioritization of preparation projects while generating archival datasets of spec...

The skeleton of a eutherian (placental) mammal has been discovered from the Lower Cretaceous Yixian Formation of northeastern China. We estimate its age to be about 125 million years (Myr), extending the date of the oldest eutherian records with skull and skeleton by about 40 50 Myr. Our analyses place the new fossil at the root of the eutherian tr...

This paper discusses the lithostratigraphy of the Xinminbao Group in the Mazongshan area of Gansu Province, northwestern China, and the correlation of its biota. The Xinminbao Group was deposited in a fluviolacustrine setting in Mesozoic graben basins under a semi-arid, subtropical climate. The fossil sites concentrated in the lower part of the gro...

Describes a demonstration in which a ball is placed in an unstable position on a saddle shape. The ball becomes stable when it is rotated above some threshold angular velocity. The demonstration is a mechanical analog of confining a particle in a "Paul Trap". (DDR)