Justin B. Lemberg

My research focuses on how changes in the skulls of early tetrapods (the ancestors of bony land animals) affected feeding mechanics during the water-to-land transition. By understanding how cranial morphology relates to feeding strategies in modern taxa, we can use those patterns to interpret the fossil record during this key transition in our own evolutionary history. Tiktaalik is an important transitional taxon that exhibits unique cranial and post-cranial morphologies that it shares with tetrapods, such as a mobile neck, an elongate rostrum, and a dorsoventrally compressed skull. By using computed tomography (CT) scans of the fossils, I am reconstructing the cranial bones and sutures for a detailed analysis of the cranial anatomy. This reconstruction is the basis of a finite element analysis (FEA) of the skull that tests for areas of high stresses and strains during simulated feeding scenarios. These data will be compared with the results of FEA on other taxa with dorsoventrally compressed skulls to search for similar strain patterns during unilateral or bilateral biting. By studying the feeding mechanics of modern analogs, such as members of Lepisosteidae, I will demonstrate form-function relationships that will bound our inferences of what we see in the fossil record.

Publications

Journal Papers

Reed, D. A., L. B. Porro, J. Iriarte-Diaz, J. B. Lemberg, C. M. Holliday, F. Anapol, and C. F. Ross. 2011. The impact of bone and suture material properties on mandibular function in Alligator mississippiensis: testing theoretical phenotypes with finite element analysis. Journal of Anatomy 218: 59-74.

Conference Abstracts: Oral

Porro, L. B., J. B. Lemberg, D. A. Reed, C. F. Ross, and K. A. Metzger. 2009. Finite element modeling of Alligator mississippiensis: multidimensional analysis, validation, and implications for fossil taxa. Journal of Vertebrate Paleontology, SVP Program and Abstracts Book 2009: 166A.

Porro, L. B., D. A. Reed, J. B. Lemberg, U. Zapata, and C. F. Ross. 2010. Mandibular mechanics of Alligator mississippiensis: from beam models to finite element analysis. Journal of Vertebrate Paleontology, SVP Program and Abstracts Book 2010: 147A.

Reed, D. A., L. B. Porro, C. M. Holliday, J. B. Lemberg, K. A. Metzger, and C. F. Ross. 2010. Multidimensional analysis of mandibular function in Alligator mississippiensis using geometric morphometrics and finite element modeling. Integrative and Comparative Biology 50: E144-E144.

Lemberg, J. B., N. K. Taft, E. B. Daeschler, and N. H. Shubin. 2011. Vascularization and dorsoventral asymmetries in the pectoral fin of Tiktaalik roseae shed light on the fin to limb transition. Journal of Vertebrate Paleontology, SVP Program and Abstracts Book 2011: 142A.

Lemberg, J. B., N. H. Shubin, C. F. Ross, and E. B. Daeschler. 2014. Digital reconstruction of the skull of Tiktaalik roseae with insights into early tetrapod feeding mechanics. Integrative and Comparative Biology 54(Suppl 1): E121.

Conference Abstracts: Poster

Lemberg, J. B., L. B. Porro, D. A. Reed, and C. F. Ross. 2009. 3D Visualization and morphometric analysis comparing mandibular sutures in a hatchling and sub-adult Alligator mississippiensis. Journal of Vertebrate Paleontology, SVP Program and Abstracts Book 2009: 134A.

Taft, N. K., J. B. Lemberg, E. B. Daeschler, and N. H. Shubin. 2012. Comparative analysis of the functional relationship between the endochondral and dermal elements of the pectoral fin among fossil and living sarcopterygian fishes. Integrative and Comparative Biology 52: E336.

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