Lessemsaurus Explained

Lessemsaurus is an extinct genus of sauropodiform dinosaur belonging to Lessemsauridae.

Naming and description

The type species, L. sauropoides, was formally described by José Fernando Bonaparte in 1999 in honor of Don Lessem, a writer of popular science books. It was found in the Los Colorados Formation of the Ischigualasto-Villa Unión Basin in La Rioja Province, Argentina.^[1]

It was discovered in strata dating to the Norian stage, around 210 million years ago.^{[2] [3]} It is estimated to have reached 10m-12mm (30feet-39feetm) long and weighed over 7MT, possibly up to 8MT10MT, in maximum body mass.^{[4] [5] [6] [7]}

Classification

A cladogram after Pol, Garrido & Cerda, 2011,^[8] illustrates a possible placing of Lessemsaurus and Antetonitrus in Sauropodomorpha:

In 2018, Apaldetti et al. recovered it as part of a clade they named Lessemsauridae, after Lessemsaurus. Their cladogram is reproduced below:^[9]

The following cladogram shows the position of Lessemsaurus outside of Sauropoda, according to Oliver W. M. Rauhut and colleagues, 2020:^[10]

Notes and References

1. Weishampel, David B; et al., 2004. "Dinosaur distribution (Late Triassic, South America)." In: Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. Pp. 527–528. .
2. Evolución de las vértebras presacras en Sauropodomorpha. Bonaparte, J. F.. José Bonaparte. 1999. Ameghiniana. 36. 115–187.
3. Pol, D. . Powell, J. E. . 2007. New information on Lessemsaurus sauropoides (Dinosauria: Sauropodomorpha) from the Upper Triassic of Argentina. Special Papers in Palaeontology. 77. 223–243.
4. Diego Pol . Alberto Garrido . Ignacio A. Cerda . 2011 . A New Sauropodomorph Dinosaur from the Early Jurassic of Patagonia and the Origin and Evolution of the Sauropod-type Sacrum . PLOS ONE . 6 . 1 . e14572 . 10.1371/journal.pone.0014572 . 21298087 . 3027623 . 2011PLoSO...614572P . free .
5. Foelix, Rainer. Pabst, Ben. Kindlimann, René. 2011. Die Saurier in Frick. Mitteilungen der aargauischen Naturforschenden Gesellschaft. 37. 10.5169/seals-283430.
6. Apaldetti, C.. Martínez, R.N.. Cerda, I.A.. Pol, D.. Alcober, O.. 2018. An early trend towards gigantism in Triassic sauropodomorph dinosaurs. Nature Ecology & Evolution. 2. 8. 1227–1232. 10.1038/s41559-018-0599-y. 29988169 . 2018NatEE...2.1227A . 11336/89332 . 256705065 . free.
7. A giant dinosaur from the earliest Jurassic of South Africa and the transition to quadrupedality in early sauropodomorphs . McPhee . Blair W. . Benson . Roger B.J. . Botha-Brink . Jennifer . Bordy . Emese M. . Choiniere . Jonah N. . amp . Current Biology . 28 . 19 . 3143–3151.e7 . 2018 . 10.1016/j.cub.2018.07.063. 30270189 . free . 2018CBio...28E3143M .
8. Diego Pol . Alberto Garrido . Ignacio A. Cerda . 2011 . A New Sauropodomorph Dinosaur from the Early Jurassic of Patagonia and the Origin and Evolution of the Sauropod-type Sacrum . PLOS ONE . 6 . 1 . e14572 . 10.1371/journal.pone.0014572 . 21298087 . 3027623 . 2011PLoSO...614572P . free .
9. Apaldetti . Martínez . Ricardo N. . Cerda . Ignatio A. . Pol . Diego . Alcober . Oscar . 2018 . An early trend towards gigantism in Triassic sauropodomorph dinosaurs . Nature Ecology & Evolution . 2 . 8 . 1227–1232 . 10.1038/s41559-018-0599-y. 11336/89332 . 29988169. 2018NatEE...2.1227A . 49669597 . free .
10. Rauhut . O. W. M. . Holwerda . F. M. . Furrer . H. . A derived sauropodiform dinosaur and other sauropodomorph material from the Late Triassic of Canton Schaffhausen, Switzerland . Swiss Journal of Geosciences . 2020 . 113 . 1 . 8 . 10.1186/s00015-020-00360-8. 220294939 . free .