Timothy Ryan

Timothy Ryan

Head and Professor of Anthropology
412 Carpenter Building University Park, PA 16802
(814) 867-0005
Timothy Ryan

Curriculum Vitae


B.A., University of New Orleans, 1994
M.A., University of Texas at Austin, 1997
Ph.D., University of Texas at Austin, 2001

Professional Bio

Professional Bio

Areas of Specialization:

Functional morphology, bone biomechanics, primate locomotion, primate and human evolution, high-resolution computed tomography, three-dimensional scientific visualization.

Research Activities and Interests:

Dr. Ryan is interested in primate and human evolutionary morphology, skeletal biology, and bone biomechanics. His research makes use of advanced computational techniques such as high-resolution computed tomography imaging and three-dimensional quantification to understand bone function and biomechanics. Dr. Ryan's research seeks to answer questions related to normal bone development, the responsiveness of bone to mechanical loading, and the relationship between specific human activity patterns and bone structure. He is currently working on projects investigating interspecific variation in trabecular bone structure in living and extinct primates, characterizing the ontogenetic development of cortical and trabecular bone in the human postcranial skeleton, and developing methods to integrate 3D geometric morphometrics and bone biomechanics. Dr. Ryan is also interested in advanced 3D imaging and scientific visualization techniques.


Magnetostratigraphy and paleontology of the Eocene Yuanqu Formation, China; paleontology of the Oligocene Chilga Formation, Ethiopia; magnetostratigraphy of the Eocene Kishenehn Formation, Montana; paleontology of the Paleocene Washakie Basin, Wyoming.

Courses Taught:

Recent Publications:

  • Ryan, T. M., & Shaw, C. N. (2013). Trabecular bone microstructure scales allometrically in the primate humerus and femur. Proceedings of the Royal Society B: Biological Sciences 280:20130172.
  • Gosman, J. H., Hubbell, Z. R., Shaw, C. N., & Ryan, T. M. (2013) Development of cortical bone geometry in the human femoral and tibial diaphysis. Anatomical Record 296:774-787.
  • Macintosh, A. A., Davies, T. G., Ryan, T. M., Shaw, C. N., & Stock, J. T. (2013). Periosteal versus true cross-sectional geometry: A comparison along humeral, femoral, and tibial diaphyses. American Journal of Physical Anthropology 150:442-452.
  • Ryan, T. M., & Shaw, C. N. (2012). Unique suites of trabecular bone features characterize locomotor behavior in human and non-human anthropoid primates. PLoS ONE, 7(7):e41037, 11.
  • Ryan, T. M., Silcox, M. T., Walker, A., Mao, X., Begun, D. R., Benefit, B. R., Gingerich, P. D., Kohler, M., Kordos, L., McCrossin, M. L., Moya-Sola, S., Sanders, W. J., Seiffert, E. R., Simons, E., Zalmout, I. S., & Spoor, F. (2012). Evolution of locomotion in Anthropoidea: the semicircular canal evidence. Proceedings of the Royal Society B: Biological Sciences 279:3467–3475.
  • Shaw, C. N., & Ryan, T. M. (2012). Does skeletal anatomy reflect adaptation to locomotor patterns? Cortical and trabecular architecture in human and non-human anthropoids. American Journal of Physical Anthropology 147:187-200.
  • Dumont, E. R., Ryan, T. M., & Godfrey, L. R. (2011). The Hadropithecus conundrum reconsidered, with implications for interpreting diet in fossil hominins. Proceedings of the Royal Society B 278:3654–3661.
  • Vinyard, C. J., Taylor, A. B., Teaford, M. F., Glander, K.E., Ravosa, M. J., Rossie, J. B., Ryan, T. M., & Williams, S. H. (2011). Are we looking for loads in all the right places? New research directions for studying the masticatory apparatus of New World monkeys. Anatomical Record 294:2140-2157.
  • Hogg, R., Vinyard, C. J., Ryan, T. M., & Ravosa, M. J. (2011). The functional morphology of the anterior masticatory apparatus in tree-gouging marmosets (Cebidae, Primates). Journal of Morphology 272:833-849.
  • Seiffert, E. R., Simons, E. L., Boyer, D. M., Perry, J. M., Ryan, T. M., & Sallam, H. M. (2010). A peculiar primate of uncertain affinities from the earliest late Eocene of Egypt. Proceedings of the National Academy of Sciences of the USA 107:9712-9717.
  • Martínez-Abadías, N., Percival, C., Aldridge, K., Hill, C. A., Ryan, T. M., Sirivunnabood, S., Wang, Y., Jabs, E. W., & Richtsmeier, J. T. (2010). Beyond the closed suture in apert syndrome mouse models: Evidence of primary effects of FGFR2 signaling on facial shape at birth. Developmental Dynamics 239:3058-3071.
  • Griffin, N. L., D’Août, K., Ryan, T. M., Richmond, B. G., Ketcham, R. A., & Postnov, A. (2010). Comparative forefoot trabecular bone architecture in extant hominids. Journal of Human Evolution 59:202-213.
  • Ryan, T. M., M. Colbert, R.A. Ketcham, and C.J. Vinyard.  (2010) Trabecular bone structure in the mandibular condyle of gouging and non-gouging platyrrhines.  American Journal of Physical Anthropology 141:583–593.
  • Ryan, T. M. and A. Walker (2010) Trabecular bone structure in the humeral and femoral heads of anthropoid primates. Anatomical Record 293:719–729.
  • Silcox, M.T., J.I. Bloch, D.M. Boyer, M. Godinot, T. M. Ryan, F. Spoor, and A. Walker. (2009) The semicircular canal system in early primates and euprimates. Journal of Human Evolution 56:315-327.
  • Welker, K., J. Orkin, and T. M. Ryan. (2009) Analysis of intra-individual and inter-sex variation in semi-circular canal dimensions using high-resolution x-ray computed tomography. Journal of Anatomy 215:444-451.
  • Ryan, T.M., D.A. Burney, L.R. Godfrey, U.B. Göhlich, W.L. Jungers, N. Vasey, Ramilisonina, A. Walker, G.W. Weber. (2008) A reconstruction of the Vienna skull of Hadropithecus stenognathus. Proceedings of the National Academy of Sciences. USA 105:10699-10702.
  • Jeffery, N., T. M. Ryan and F. Spoor. (2008) The primate subarcuate fossa and its relationship to the semicircular canals part II: adult interspecific variations. Journal of Human Evolution 55:326-339.
  • Walker, A., T. M. Ryan, M.T. Silcox, E. Simons, F. Spoor. (2008) The semicircular canal system and locomotion: the case of extinct lemuroids and lorisoids. Evolutionary Anthropology 17:135-145.
  • Seiffert, E.R., E.L. Simons, T. M. Ryan, T.M. Bown, and Y. Attia. (2007) New remains of Eocene and Oligocene Afrosoricida (Afrotheria) from Egypt, with implications for the origin(s) of afrosoricid zalambdodonty. Journal of Vertebrate Paleontology 27:963-972.
  • Spoor, F., T. Garland Jr., G. Krovitz, T. M. Ryan, M.T. Silcox, and A. Walker. (2007) The primate semicircular canal system and locomotion. Proceedings of the National Academy of Sciences USA 104:10808-10812.
  • Fraser, N.E., P. E. Olsen, A.C. Dooley, and T.M. Ryan. (2007)   A new gliding tetrapod (Diapsida: ?Archosauromorpha) from the Upper Triassic (Carnian) of Virginia. Journal of Vertebrate Paleontology 27:261-265.
  • Simons, E.L., E.R. Seiffert, T.M. Ryan, and Y. Attia. (2007) A remarkable female cranium of the early Oligocene anthropoid Aegyptopithecus zeuxis (Catarrhini, Propliopithecidae). Proceedings of the National Academy of Sciences USA 104:8731-8736.
  • Parsons, T., T. M. Ryan, R.H. Reeves, and J. Richtsmeier. (2007) Micro-structure of trabecular bone in a mouse model for Down syndrome. The Anatomical Record 290:414-421.
  • Vinyard, C. J. and T. M. Ryan. (2006) Cross-sectional bone distribution in the mandibles of gouging and non-gouging platyrrhines.International Journal of Primatology 27:1461-1490.
  • Ryan, T. M. and G.E. Krovitz. (2006) Trabecular bone ontogeny in the human proximal femur. Journal of Human Evolution 51:591-602.
  • Ryan, T.M. and G.R. Milner. (2006) Osteological applications of high-resolution computed tomography: A prehistoric arrow injury.Journal of Archaeological Science 33:871-879.
  • Maga, M., J. Kappelman, T.M. Ryan, and R.A. Ketcham. (2006) The calcaneal trabecular microarchitecture of extant large bodied hominoids. American Journal of Physical Anthropology 129:410-417.
  • Seiffert, E.R., E.L. Simons, T.M. Ryan, and Y. Attia. (2005) Additional remains of Wadilemur elegans, a primitive stem galagid from the late Eocene of Egypt. Proceedings of the National Academy of Sciences USA. 102:11396-11401.
  • Ryan, T. M. and R. A. Ketcham. (2005) The angular orientation of trabecular bone in the femoral head and its relationship to hip joint loads in leaping primates. Journal of Morphology 265:249-263.
  • Ryan, T. M. and B. van Rietbergen. (2005) Mechanical significance of femoral head trabecular bone structure in Loris and Galago evaluated using micromechanical finite element models. American Journal of Physical Anthropology 126:82-96.
  • Ketcham, R. A. and T. M. Ryan. (2004) Quantification of anisotropy in trabecular bone. Journal of Microscopy 213:158-171.
  • Kappelman, J., D. T. Rasmussen, W. J. Sanders, M. Feseha, T. Bown, P. Copeland, J. Crabaugh, J. Fleagle, M. Glantz, A. Gordon, B. Jacobs, M. Maga, K. Muldoon, A. Pan, L. Pyne, B. Richmond, T. Ryan, E. R. Seiffert, S. Sen, L. Todd, M. C. Wiemann, A. Winkler. (2003) Oligocene mammals from Ethiopia and faunal exchange between Afro-Arabia and Eurasia. Nature 426:549-552
  • Ryan, T. M. and R. A. Ketcham. (2002) Femoral head trabecular bone structure in two omomyid primates. Journal of Human Evolution 43:241-263.
  • Ryan, T. M. and R. A. Ketcham. (2002) The three-dimensional structure of trabecular bone in the femoral head of strepsirrhine primates. Journal of Human Evolution 43:1-26.
  • Fajardo, R. J., T. M. Ryan, and J. Kappelman. (2002) Assessing the accuracy of high-resolution X-ray computed tomography of primate trabecular bone by comparisons with histological sections. American Journal of Physical Anthropology 118:1-10.