Ron Heinrich , Instructor
 
 

B.Sc. University of Saskatchewan

Ph.D. Johns Hopkins School of Medicine

Research
 

Vertebrate Morphology and Evolution

My research interests relate to the early evolution and diversification of the mammalian order Carnivora and to the way in which both fossil and living carnivores utilize their limbs during locomotion and associated behaviors (e.g. digging).  An offshoot of this research has been an attempt to understand how the shape of long bones changes in response to increasing body mass during the lifetime of an animal, a field of study referred to as ontogenetic allometry.

Carnivora includes an extremely diverse array of mammals that vary considerably in size, shape, and ecology.  Besides cats and dogs the order includes weasels, mongooses, raccoons, bears, hyaenas, and the marine-adapted seals and walruses all of which evolved from a group of carnivorans, the miacoids, that lived some 65-45 million years ago. The oldest known miacoid skeletons appear in the fossil record about 55 million years ago and much of my work to date has involved describing these fossils and comparing them to modern mammals (Fig. 1) where we can correlate the size and shape of the bone with specific behaviors. Using this comparative morphology approach we are able to provide some interpretation of the extent to which these extinct animals used their limbs for climbing, digging running, etc.
 

Figure 1. Comparison of the humeri of the fossil miacids Vulpavus (A) and Didymictis (B)to the living carnivorans, the arboreal binturong (C) and the wolf (D). Like the binturongVulpavus possesses a low greater tubercle (gt) and well-developed lesser tubercle (lt) for attachment of the rotator cuff muscles of the shoulder . Didymictis is more similar to the wolf in these features and also possesses a supratrochelar foramen (sf) characteristic of mammals that are adapted for terrestrial speed rather than climbing although Didymicits possesses a well-developed medial epicondyle (me) indicative of strong forearm flexors. From Heinrich and Rose, 1997.
 
 

I have also employed a more biomechanical approach to understanding the skeleton of fossil carnivorans, an approach that involves modeling bones as beams and then analyses bone shape using basic engineering principles.  By comparing the amount and distribution of bone at different cross sections along the length of particular long bones such as the humerus and femur (Fig. 2), we can get some idea of the mechanical forces that acted on that bone when the animal was alive.  This has led to collaboration with other researchers in studies that analyze the forces carnivorans exert on the ground with their fore- and hindlimbs when walking and running.  I anticipate that these broader studies of mammalian locomotion will enable me to describe more definitively the locomotor behaviors of extinct species. Cross-sectional parameters have also provided an important means for estimating body mass of fossils, and I have applied this technique to the early miacids.
 
 

Figure 2. Orientations and reference axes of the humerus (A) and femur (B) of a wolverine used to acquire cross-sectional data. From these cross sections (C and D respectively) parameters such as cortical area and moments of area can be calculated that provide information regarding axial and bending rigidity of the bone at that particular section. From Heinrich and Biknevicius, 1998.

Publications

Weishampel, D.B. and R.E. Heinrich. 1992. Systematics of the Hypsilophodontidae and Basal

Courses Taught

Introductory Zoology Labs (Bios 171, 173)

Human Anatomy (Bios 301/302)

Advanced Human Anatomy (Bios 401)

Address, Phone, E-mail

Department of Biological Sciences

Ohio University

Athens, Ohio 45701

(740) 593 - 9485

heinrich@ohio.edu