Lessemsaurus

Lessemsaurus is an extinct genus of sauropodiform dinosaur that lived in the Norian-aged Los Colorados Formation of what is now Argentina.

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].
It is part of the La Esquina faunal assemblage, dating to the mid-Norian stage, around 213 million years ago. It is estimated to have reached long and weighed over, possibly up to, in maximum body mass.

Classification

A cladogram after Pol, Garrido & Cerda, 2011, 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:
The following cladogram shows the position of Lessemsaurus outside of Sauropoda, according to Oliver W. M. Rauhut and colleagues, 2020: