Lessemsaurus is an extinct genus of sauropodiform dinosaur that lived in the Norian-aged (Upper Triassic) 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 10–12 metres (33–39 ft) long and weighed over 7 metric tons (7.7 short tons), possibly up to 8–10 metric tons (8.8–11.0 short tons), in maximum body mass.

Classification

Exhibit in Singapore

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

SauropodomorphaSaturnalia Pantydraco Thecodontosaurus Efraasia Ruehleia Plateosaurus Massopoda Riojasaurus Massospondylus Coloradisaurus Lufengosaurus Gyposaurus Yunnanosaurus Anchisauria Anchisaurus Aardonyx Leonerasaurus Melanorosaurus Sauropoda Antetonitrus Lessemsaurus Kotasaurus Vulcanodon Eusauropoda
Saturnalia
Pantydraco Thecodontosaurus Efraasia Ruehleia Plateosaurus Massopoda Riojasaurus Massospondylus Coloradisaurus Lufengosaurus Gyposaurus Yunnanosaurus Anchisauria Anchisaurus Aardonyx Leonerasaurus Melanorosaurus Sauropoda Antetonitrus Lessemsaurus Kotasaurus Vulcanodon Eusauropoda
Pantydraco Thecodontosaurus
Pantydraco
Thecodontosaurus
Efraasia Ruehleia Plateosaurus Massopoda Riojasaurus Massospondylus Coloradisaurus Lufengosaurus Gyposaurus Yunnanosaurus Anchisauria Anchisaurus Aardonyx Leonerasaurus Melanorosaurus Sauropoda Antetonitrus Lessemsaurus Kotasaurus Vulcanodon Eusauropoda
Efraasia
Ruehleia Plateosaurus Massopoda Riojasaurus Massospondylus Coloradisaurus Lufengosaurus Gyposaurus Yunnanosaurus Anchisauria Anchisaurus Aardonyx Leonerasaurus Melanorosaurus Sauropoda Antetonitrus Lessemsaurus Kotasaurus Vulcanodon Eusauropoda
Ruehleia
Plateosaurus
MassopodaRiojasaurus Massospondylus Coloradisaurus Lufengosaurus Gyposaurus Yunnanosaurus Anchisauria Anchisaurus Aardonyx Leonerasaurus Melanorosaurus Sauropoda Antetonitrus Lessemsaurus Kotasaurus Vulcanodon Eusauropoda
Riojasaurus
Massospondylus Coloradisaurus Lufengosaurus Gyposaurus Yunnanosaurus Anchisauria Anchisaurus Aardonyx Leonerasaurus Melanorosaurus Sauropoda Antetonitrus Lessemsaurus Kotasaurus Vulcanodon Eusauropoda
Massospondylus Coloradisaurus Lufengosaurus Gyposaurus Yunnanosaurus
Massospondylus
Coloradisaurus Lufengosaurus Gyposaurus Yunnanosaurus
Coloradisaurus
Lufengosaurus
Gyposaurus
Yunnanosaurus
AnchisauriaAnchisaurus Aardonyx Leonerasaurus Melanorosaurus Sauropoda Antetonitrus Lessemsaurus Kotasaurus Vulcanodon Eusauropoda
Anchisaurus
Aardonyx Leonerasaurus Melanorosaurus Sauropoda Antetonitrus Lessemsaurus Kotasaurus Vulcanodon Eusauropoda
Aardonyx
Leonerasaurus Melanorosaurus Sauropoda Antetonitrus Lessemsaurus Kotasaurus Vulcanodon Eusauropoda
Leonerasaurus
Melanorosaurus Sauropoda Antetonitrus Lessemsaurus Kotasaurus Vulcanodon Eusauropoda
Melanorosaurus
SauropodaAntetonitrus Lessemsaurus Kotasaurus Vulcanodon Eusauropoda
Antetonitrus Lessemsaurus
Antetonitrus
Lessemsaurus
Kotasaurus Vulcanodon Eusauropoda
Kotasaurus
Vulcanodon Eusauropoda
Vulcanodon
Eusauropoda

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

SauropodiformesMussaurus Aardonyx Sefapanosaurus Melanorosauridae Camelotia Melanorosaurus Sauropoda Lessemsauridae Antetonitrus Ingentia Lessemsaurus Blikanasaurus Gongxianosaurus Pulanesaura Gravisauria
Mussaurus
Aardonyx Sefapanosaurus Melanorosauridae Camelotia Melanorosaurus Sauropoda Lessemsauridae Antetonitrus Ingentia Lessemsaurus Blikanasaurus Gongxianosaurus Pulanesaura Gravisauria
Aardonyx
Sefapanosaurus
Melanorosauridae Camelotia Melanorosaurus Sauropoda Lessemsauridae Antetonitrus Ingentia Lessemsaurus Blikanasaurus Gongxianosaurus Pulanesaura Gravisauria
Melanorosauridae Camelotia Melanorosaurus
MelanorosauridaeCamelotia Melanorosaurus
Camelotia
Melanorosaurus
Sauropoda Lessemsauridae Antetonitrus Ingentia Lessemsaurus Blikanasaurus Gongxianosaurus Pulanesaura Gravisauria
SauropodaLessemsauridae Antetonitrus Ingentia Lessemsaurus Blikanasaurus Gongxianosaurus Pulanesaura Gravisauria
Lessemsauridae Antetonitrus Ingentia Lessemsaurus
LessemsauridaeAntetonitrus Ingentia Lessemsaurus
Antetonitrus
Ingentia Lessemsaurus
Ingentia
Lessemsaurus
Blikanasaurus Gongxianosaurus Pulanesaura Gravisauria
Blikanasaurus
Gongxianosaurus Pulanesaura Gravisauria
Gongxianosaurus
Pulanesaura Gravisauria
Pulanesaura
Gravisauria

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

MassopodaEucnemesaurus Riojasaurus Sarahsaurus Massospondylidae Yunnanosaurus Jingshanosaurus Seitaad Coloradisaurus Glacialisaurus Lufengosaurus Massospondylus Adeopapposaurus Leyesaurus Sauropodiformes Xingxiulong Anchisaurus Leonerasaurus Mussaurus Aardonyx Sefapanosaurus Meroktenos Melanorosaurus Camelotia Lessemsaurus Antetonitrus Ingentia Blikanasaurus Pulanesaura Gongxianosaurus Schleitheimia Isanosaurus Tazoudasaurus Sauropoda
Eucnemesaurus Riojasaurus
Eucnemesaurus
Riojasaurus
Sarahsaurus Massospondylidae Yunnanosaurus Jingshanosaurus Seitaad Coloradisaurus Glacialisaurus Lufengosaurus Massospondylus Adeopapposaurus Leyesaurus Sauropodiformes Xingxiulong Anchisaurus Leonerasaurus Mussaurus Aardonyx Sefapanosaurus Meroktenos Melanorosaurus Camelotia Lessemsaurus Antetonitrus Ingentia Blikanasaurus Pulanesaura Gongxianosaurus Schleitheimia Isanosaurus Tazoudasaurus Sauropoda
Sarahsaurus
Massospondylidae Yunnanosaurus Jingshanosaurus Seitaad Coloradisaurus Glacialisaurus Lufengosaurus Massospondylus Adeopapposaurus Leyesaurus Sauropodiformes Xingxiulong Anchisaurus Leonerasaurus Mussaurus Aardonyx Sefapanosaurus Meroktenos Melanorosaurus Camelotia Lessemsaurus Antetonitrus Ingentia Blikanasaurus Pulanesaura Gongxianosaurus Schleitheimia Isanosaurus Tazoudasaurus Sauropoda
MassospondylidaeYunnanosaurus Jingshanosaurus Seitaad Coloradisaurus Glacialisaurus Lufengosaurus Massospondylus Adeopapposaurus Leyesaurus
Yunnanosaurus Jingshanosaurus Seitaad
Yunnanosaurus
Jingshanosaurus Seitaad
Jingshanosaurus
Seitaad
Coloradisaurus Glacialisaurus Lufengosaurus Massospondylus Adeopapposaurus Leyesaurus
Coloradisaurus Glacialisaurus Lufengosaurus
Coloradisaurus
Glacialisaurus Lufengosaurus
Glacialisaurus
Lufengosaurus
Massospondylus Adeopapposaurus Leyesaurus
Massospondylus
Adeopapposaurus Leyesaurus
Adeopapposaurus
Leyesaurus
SauropodiformesXingxiulong Anchisaurus Leonerasaurus Mussaurus Aardonyx Sefapanosaurus Meroktenos Melanorosaurus Camelotia Lessemsaurus Antetonitrus Ingentia Blikanasaurus Pulanesaura Gongxianosaurus Schleitheimia Isanosaurus Tazoudasaurus Sauropoda
Xingxiulong
Anchisaurus Leonerasaurus Mussaurus Aardonyx Sefapanosaurus Meroktenos Melanorosaurus Camelotia Lessemsaurus Antetonitrus Ingentia Blikanasaurus Pulanesaura Gongxianosaurus Schleitheimia Isanosaurus Tazoudasaurus Sauropoda
Anchisaurus Leonerasaurus
Anchisaurus
Leonerasaurus
Mussaurus Aardonyx Sefapanosaurus Meroktenos Melanorosaurus Camelotia Lessemsaurus Antetonitrus Ingentia Blikanasaurus Pulanesaura Gongxianosaurus Schleitheimia Isanosaurus Tazoudasaurus Sauropoda
Mussaurus
Aardonyx Sefapanosaurus Meroktenos Melanorosaurus Camelotia Lessemsaurus Antetonitrus Ingentia Blikanasaurus Pulanesaura Gongxianosaurus Schleitheimia Isanosaurus Tazoudasaurus Sauropoda
Aardonyx
Sefapanosaurus Meroktenos Melanorosaurus Camelotia Lessemsaurus Antetonitrus Ingentia Blikanasaurus Pulanesaura Gongxianosaurus Schleitheimia Isanosaurus Tazoudasaurus Sauropoda
Sefapanosaurus
Meroktenos Melanorosaurus Camelotia Lessemsaurus Antetonitrus Ingentia Blikanasaurus Pulanesaura Gongxianosaurus Schleitheimia Isanosaurus Tazoudasaurus Sauropoda
Meroktenos
Melanorosaurus Camelotia Lessemsaurus Antetonitrus Ingentia Blikanasaurus Pulanesaura Gongxianosaurus Schleitheimia Isanosaurus Tazoudasaurus Sauropoda
Melanorosaurus
Camelotia Lessemsaurus Antetonitrus Ingentia Blikanasaurus Pulanesaura Gongxianosaurus Schleitheimia Isanosaurus Tazoudasaurus Sauropoda
Camelotia
Lessemsaurus Antetonitrus Ingentia Blikanasaurus Pulanesaura Gongxianosaurus Schleitheimia Isanosaurus Tazoudasaurus Sauropoda
Lessemsaurus Antetonitrus Ingentia
Lessemsaurus
Antetonitrus Ingentia
Antetonitrus
Ingentia
Blikanasaurus Pulanesaura Gongxianosaurus Schleitheimia Isanosaurus Tazoudasaurus Sauropoda
Blikanasaurus
Pulanesaura Gongxianosaurus Schleitheimia Isanosaurus Tazoudasaurus Sauropoda
Pulanesaura
Gongxianosaurus Schleitheimia Isanosaurus Tazoudasaurus Sauropoda
Gongxianosaurus
Schleitheimia Isanosaurus Tazoudasaurus Sauropoda
Schleitheimia
Isanosaurus Tazoudasaurus Sauropoda
Isanosaurus
Tazoudasaurus Sauropoda
Tazoudasaurus
Sauropoda

External links

  • Media related to Lessemsaurus at Wikimedia Commons