Ontogeny and evolution of sensory perception in temnospondyls

Temnospondyls, ranging from the Mississippian to the late Early Cretaceous, were a highly diverse group of early tetrapods that occupied aquatic, semiterrestrial, and terrestrial habitats. Their life cycles often involved habitat shifts, such as transitions from aquatic to terrestrial environments, and they spanned a remarkable body-size range from a few centimeters to more than five meters. This ecological and morphological diversity makes temnospondyls an excellent group for studying how early tetrapods adapted their sensory systems during ecological and evolutionary diversification.

Project aim

This project aims to reconstruct aspects of temnospondyl life history from a physiological perspective by examining evolutionary changes in three sensory systems with well-preserved osteological correlates: 

1. the hearing system, represented by the squamosal embayment, middle ear cavity, and stapes; 
2. the visual system, reflected in the orbits, scleral rings, and palpebral bones;
3. the mechanoreceptive lateral line system, which in aquatic taxa formed canals or grooves in the dermal bones of the skull and mandible.

Methods

The project conducts a systematic comparative study of these systems across numerous species representing the major temnospondyl groups and ecological strategies. The research combines classical morphology, histology, landmark-based geometric morphometrics, 3D surface scanning, synchrotron X-ray phase-contrast tomography, and micro-CT. Analyses are interpreted in light of the paleoenvironmental settings and inferred lifestyles of the studied taxa. Comparisons with the morphology and sensory capabilities of extant lissamphibians and bony fishes, based on literature and direct study, provide an important modern framework.

In the final stage, data on osteological correlates of hearing, vision, and lateral-line sensitivity will be integrated to produce a comprehensive picture of sensory evolution in temnospondyls. This will allow us to evaluate how phylogeny and ecological factors such as habitat influenced the relative importance and interaction of these sensory systems.

Collaborating partners

• Lars Schmitz, Claremont McKenna College, Claremont, CA, USA

• Marcello Ruta, University of Lincoln, UK