Resizing Lisowicia bojani: volumetric body mass estimate and 3D reconstruction of the giant Late Triassic dicynodont

ABSTRACT

Body size is one of the most crucial biological properties, with a major influence on ecology, metabolism and several physiological aspects. Recently the exceptionally large dicynodont Lisowicia bojani from the Late Triassic of Poland has been described. Using a regression formula based on long bone circumferences, an impressive body mass of 9.33 tons was reconstructed in the original description for this new and largest member of dicynodonts. The taxon is characterized by particularly robust long bones with very massive and stout shafts, thus raising the theoretical possibility that the regression formulae may have led to a substantial overestimate of the body mass. Here we present a new body mass estimate for Lisowicia based on 3D digital volumetric models, aiming to provide a more reliable and conservative estimate. The new body mass ranges from 4.87 tons to 7.02 tons for the adult taxon, with an average body mass of 5.88 tons; thus, the original value of 9.33 tons overestimates the weight of about 60%. Our study confirms empirically that volumetric methods for body mass estimates should be preferred and implemented whenever possible. Synapsids still had to wait until the Eocene to reach the enormous body mass of 9 tons.

KEYWORDS:

• Body mass estimate
• 3D model
• photogrammetry
• Dicynodontia
• Late Triassic

Acknowledgments

Grzegorz Niedzwiedzki is warmly thanked for useful discussions on the general structure of Lisowicia, especially regarding the width of the ribcage. The Editor and two anonymous reviewers are warmly thanked for their comments that improved the manuscript. Abby Gancz is warmly thanked for providing the 3D photogrammetric model of the African Elephant exhibited at the Smithsonian available under the Creative Commons Attribution license at https://www.thingiverse.com/thing:2394471 (no changes to the original model have been made). Funding was provided by the DST/NRF Centre of Excellence for Palaeosciences (CoE in Palaeosciences), the NRF African Origins Platform, and the Paleontological Society Sepkoski Grant 2018 to M.R.

Disclosure statement

No potential conflict of interest was reported by the authors.