Welcome to the Best Feet Forward (BFF) Locomotion Lab!
We would like to understand how ancient reptiles and early mammals moved about, but without a time machine, we can’t put them on a treadmill. Instead, our lab focuses on the movement and evolutionary implications of forelimb posture in reptiles, birds, and mammals. We utilize optical tracking technology to track regional movements in the forelimbs, XROMM (X-ray Reconstruction of Moving Morphology) to understand the three-dimensional movements of forelimb bones, and morphometrics to tie bone shape to movement parameters. Our ultimate goal is to realistically model and place constraints on how fossil vertebrates, such as dinosaurs and early mammals, moved their forelimbs.
Follow us on Twitter! @BFFLocomotion
Detailed Research Plan
The Evolution of Upright Forelimb Posture in Amniote Vertebrates
Amniotes (those vertebrates that possess a specialized egg and embryo for life on land) are represented today by two major radiations of vertebrates: the Reptilia (including birds) and the Mammalia (Shedlock and Edwards, 2009). Despite their differences, both groups descended from a common ancestor that had a sprawling forelimb posture (Benton, 2005). In both lineages, an upright forelimb posture was achieved, but apparently in different ways. On the Mammalia line, an erect forelimb evolved in Therian mammals (marsupials and placentals), whereas quadrupedal dinosaurs developed an erect forelimb on the Reptilia line. However, especially for dinosaurs, it has remained difficult and challenging to reconstruct forelimb posture and locomotion because, unlike mammals, the joints of these reptiles were less congruent and covered in thick cartilage that does not fossilize (Bonnan et al., 2010; Holliday et al., 2010). Furthermore, the challenge to transitioning from a sprawled to an erect posture requires that the hand (forefoot or manus) must be rotated into a position that supports body mass and propels the animal forwards. The hand must flex and extend in the same plane as the hind foot (pes) with the fingers facing anteriorly and the palm facing posteriorly, a posture called pronation. In both mammals and reptilians, pronation is often accomplished by internal movements and rotations of the forearm bones (radius and ulna) impossible to see with just the naked eye.
We are using two different but complimentary approaches to get at our lab questions. One method involves the use of optical markers that are tracked with specialized infrared cameras and software. In particular, we utilize the OptiTrack V120 Trio system and analyze our data with Mokka software and MATLAB.
The other method is called XROMM (X-ray Reconstruction of Moving Morphology). In a nutshell, calibrated videofluoroscopes (essentially, high speed video cameras connected to x-ray fluoroscopes) capture animal locomotion in two planes that can be interpolated into a 3-D moving skeletal model. XROMM is used to investigate the actual movements and orientations of the bones in our lab animals without relying on inferences from dissection or external markers. Seeing and mapping these movements is critical because we want to know how similar and different bone kinematics are among different amniotes, and how this effects their forelimb posture.
Long bones are living tissues that change their shape to best resist the major repetitive forces acting on them (Carter and Beaupré, 2001). Therefore, posture and locomotion are correlated with bone shape. Although we cannot run a dinosaur or fossil mammal on a treadmill, if it were possible to quantify and describe long bone movements and typical postures in living vertebrates, we can then correlate living mammal and reptile forelimb bone movements with their shapes. Thus, we could use the shape of fossil animal bones to accurately infer how these extinct organisms moved based on how closely these shapes overlap with those of living vertebrates whose range of movements are known and quantified. Ultimately, such an approach would quantitatively correlate bone movements and shape so that the possible range of locomotor postures in fossil amniotes could be more accurately constrained. When such data are mapped onto a phylogeny, the evolutionary origin and pattern by which both mammals and dinosaurs achieved an upright forelimb with a pronated hand can be illuminated.
Matthew F. Bonnan, Ph.D. – Associate Professor, Biology Program
Jason Shulman, Ph.D. – Assistant Professor, Physics Program
Current Student Groups
Lizard Forelimb Kinematics – “Bonnan’s Beardies”
Small/Crouched Mammal Forelimb Kinematics
Evan Drake, who helped with the initial XROMM animations for our rat forelimb research.
Kadeisha Pinkney, who helped analyze the data of our rat XROMM forelimb research.
Radha Varadharajan, now applying to several vet schools, shown below collected data on rat locomotion in the Brown University XROMM C-arms lab.
Cailin Bader, who helped with collecting data on forelimb locomotion in leopard geckos.
Celia Rodriguez, who helped with collecting data on forelimb locomotion in leopard geckos.
Species we are currently studying in our lab:
Varanus exanthematicus – Savannah monitors
Rattus norvegicus – “Norway” rats
Mustela putorius furo – Domestic ferrets
Presentations and Publications
Our presentations at the 3rd Annual Northeast Regional Vertebrate Evolution Symposium at the American Museum of Natural History:
Evan DRAKE, KADEISHA PINKNEY, RADHA VARADHARAJAN, JASON SHULMAN,
AND MATTHEW F. BONNAN. Using XROMM to test the mobility of the radius and
ulna during locomotion in Rattus norvegicus: implications for fossil eutherians.
CALEB BAYEWU, KELSEY GAMBLE, JASON SHULMAN, J., AND MATTHEW F.
BONNAN. How upright is upright? Investigating forelimb posture during walking
in Rattus norvegicus using 3-D optical tracking: a pilot study.
CAILIN BADER, COREY BARNES, CELIA RODRIGUEZ, JASON SHULMAN, AND
MATTHEW F. BONNAN. Forelimb posture during walking in leopard geckos
(Eublepharis macularius) using 3-D optical tracking: a pilot study on a basal
Our presentations at the 2nd Annual Northeast Regional Vertebrate Evolution Symposium at the New York Institute of Technology (NYIT):
Varadharajan, R. and Bonnan, M. F. 2013. Exploring 3-D long bone kinematics in the White Rat (Rattus norvegicus) as a model for inferring forelimb posture in early mammals: Contribution of the scapula. Northeastern Regional Symposium on Vertebrate Evolutionary Morphology, March 22, 2013. New York Institute of Technology, College of Osteopathic Medicine
Pinkney, K. and Bonnan, M. F. 2013. Exploring 3-D long bone kinematics in the White Rat (Rattus norvegicus) as a model for inferring forelimb posture in early mammals: Contribution of the humerus. Northeastern Regional Symposium on Vertebrate Evolutionary Morphology, March 22, 2013. New York Institute of Technology, College of Osteopathic Medicine.
Drake, E. and Bonnan, M.F. 2013. Exploring 3-D long bone kinematics in the White Rat (Rattus norvegicus) as a model for inferring forelimb posture in early mammals: Contribution of the radius and ulna. Northeastern Regional Symposium on Vertebrate Evolutionary Morphology, March 22, 2013. New York Institute of Technology, College of Osteopathic Medicine.