Lessemsauridae

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Lessemsaurids
Temporal range:
Late Triassic-Early Jurassic, 218–193  Ma
Lessemsaurus Senckenberg.jpg
Skeletal mount of Lessemsaurus
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Saurischia
Clade: Sauropodomorpha
Clade: Sauropoda
Clade: Lessemsauridae
Apaldetti et al., 2018
Genera

Lessemsauridae is a clade of early sauropodiform dinosaurs that lived in the Triassic and Jurassic of Argentina, South Africa and possibly Lesotho. A phylogenetic analysis performed by Apaldetti and colleagues in 2018 recovered a new clade of sauropodiforms uniting Lessemsaurus , Antetonitrus , and Ingentia which they named Lessemsauridae. It is a node-based taxon, defined as all descendants of the most recent common ancestor of Lessemsaurus sauropoides and Antetonitrus ingenipes. [1] Depending on the definition of Sauropoda, Lessemsauridae is either one of the most basal sauropod taxa, or a sister taxon of Sauropoda. An additional member of the clade was named later in 2018, Ledumahadi . [2] A 2021 study by Pol and colleagues also assigned the genera Kholumolumo and Meroktenos to the group. [3]

Contents

Description

Lessemsaurids were quadrupeds. Unlike later sauropods, which had columnar limbs, the forelimbs of lessemsaurids were flexed. [2] Sauropodomorph trackways have been found with widely-spaced front feet, indicating they were made by a trackmaker with flexed forelimbs as in lessemsaurids. [4]

Lessemsaurids could reach large sizes, with Lessemsaurus estimated to have reached a mass of 7 tonnes [1] and the later Ledumahadi estimated to have reached a mass of 12 tonnes. [2]

They had highly pneumatic cervical and dorsal vertebrae, very antero-posteriorly short but tall cervical vertebrae, robust cervicals, a very expanded distal scapula blade, and upright arms. [1] [2]

Evolution and biogeography

Lessemsaurids first appeared during the middle Norian age of the Triassic. A specimen of an unnamed lessemsaurid from the Elliot Formation of South Africa probably dates to approximately 218 million years ago. [5] Lessemsaurus is a member of the La Esquina Local Fauna, [3] which probably dates to at least 213 million years ago. [6] Antetonitrus and Ledumahadi are found in the Upper Elliot Formation, which dates to the Hettangian and Sinemurian ages of the Jurassic. [7] Lessemsaurids are known from South Africa and Argentina.

Related Research Articles

<span class="mw-page-title-main">Sauropodomorpha</span> Extinct clade of dinosaurs

Sauropodomorpha is an extinct clade of long-necked, herbivorous, saurischian dinosaurs that includes the sauropods and their ancestral relatives. Sauropods generally grew to very large sizes, had long necks and tails, were quadrupedal, and became the largest animals to ever walk the Earth. The prosauropods, which preceded the sauropods, were smaller and were often able to walk on two legs. The sauropodomorphs were the dominant terrestrial herbivores throughout much of the Mesozoic Era, from their origins in the Late Triassic until their decline and extinction at the end of the Cretaceous.

<i>Melanorosaurus</i> Sauropodomorph dinosaur genus from the Late Triassic period

Melanorosaurus is a genus of basal sauropodomorph dinosaur that lived during the Late Triassic period. A herbivore from South Africa, it had a large body and sturdy limbs, suggesting it moved about on all fours. Its limb bones were massive and heavy like the limb bones of true sauropods.

<i>Massospondylus</i> Sauropodomorph dinosaur genus from Early Jurassic South Africa and Botswana

Massospondylus was a genus of sauropodomorph dinosaur from the Early Jurassic. It was described by Sir Richard Owen in 1854 from remains discovered in South Africa, and is thus one of the first dinosaurs to have been named. Fossils have since been found at other locations in South Africa, Lesotho, and Zimbabwe. Material from Arizona's Kayenta Formation, India, and Argentina has been assigned to the genus at various times, but the Arizonan and Argentinian material are now assigned to other genera.

<i>Lessemsaurus</i> Sauropod dinosaur genus from Late Triassic Argentina

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

<i>Antetonitrus</i> Sauropod dinosaur genus from Early Jurassic South Africa

Antetonitrus is a genus of sauropod dinosaur found in the Early Jurassic Elliot Formation of South Africa. The only species is Antetonitrus ingenipes. As one of the oldest known sauropods, it is crucial for the understanding of the origin and early evolution of this group. It was a quadrupedal herbivore, like all of its later relatives, but shows primitive adaptations to use the forelimbs for grasping, instead of purely for weight support.

<i>Blikanasaurus</i> Extinct genus of dinosaur from the late Triassic of South Africa

Blikanasaurus is a genus of sauropodomorph dinosaur from the late Triassic of South Africa. The generic name Blikanasaurus is derived from Greek, meaning "lizard from Blikana". The species name cromptoni is taken from the surname of A.W. “Fuzz” Crompton, an American paleontologist who led numerous field expeditions in Elliot Formation outcrop localities in South Africa. Blikanasaurus is only known from partial hindlimb bones that were recovered from the lower Elliot Formation (LEF) in the Eastern Cape.

<i>Coloradisaurus</i> Extinct genus of dinosaurs

Coloradisaurus is a genus of massospondylid sauropodomorph dinosaur. It lived during the Late Triassic period in what is now La Rioja Province, Argentina. It is known from two specimens collected from the Los Colorados Formation of the Ischigualasto-Villa Unión Basin.

<span class="mw-page-title-main">Clarens Formation</span> Geological formation of the Stormberg Group in southern Africa

The Clarens Formation is a geological formation found in several localities in Lesotho and in the Free State, KwaZulu-Natal, and Eastern Cape provinces in South Africa. It is the uppermost of the three formations found in the Stormberg Group of the greater Karoo Supergroup rocks and represents the final phase of preserved sedimentation of the Karoo Basin.

<span class="mw-page-title-main">Massospondylidae</span> Extinct family of dinosaurs

Massospondylidae is a family of early massopod dinosaurs that existed in Asia, Africa, North America, South America and Antarctica during the Late Triassic to the Early Jurassic periods. Several dinosaurs have been classified as massospondylids over the years. The largest cladistic analysis of early sauropodomorphs, which was presented by Apaldetti and colleagues in November 2011, found Adeopapposaurus, Coloradisaurus, Glacialisaurus, Massospondylus, Leyesaurus and Lufengosaurus to be massospondylids. This result supports many previous analyses that tested fewer taxa. However, this analysis found the two recently described North American massopods, Sarahsaurus and Seitaad, and the South African Ignavusaurus to nest outside Massospondylidae, as opposed to some provisional proposals. Earlier in 2011, Pradhania, a sauropodomorph from India, was tested for the first time in a large cladistic analysis and was found to be a relatively basal massospondylid. Mussaurus and Xixiposaurus may also be included within Massospondylidae.

<span class="mw-page-title-main">Anchisauria</span> Extinct clade of dinosaurs

Anchisauria is an extinct clade of sauropodomorph dinosaurs that lived from the Late Triassic to the Late Cretaceous. The name Anchisauria was first used Haekel and defined by Galton and Upchurch in the second edition of The Dinosauria. It is a node-based taxon containing the most recent common ancestor of Anchisaurus polyzelus and Melanorosaurus readi, and all its descendants. Galton and Upchurch assigned a family of dinosaurs to the Anchisauria: the Melanorosauridae. The more common prosauropods Plateosaurus and Massospondylus were placed in the sister clade Plateosauria.

<span class="mw-page-title-main">Plateosauria</span> Extinct clade of dinosaurs

Plateosauria is a clade of sauropodomorph dinosaurs which lived during the Late Triassic to the Late Cretaceous. The name Plateosauria was first coined by Gustav Tornier in 1913. The name afterwards fell out of use until the 1980s.

<span class="mw-page-title-main">Massopoda</span> Extinct clade of dinosaurs

Massopoda is a clade of sauropodomorph dinosaurs which lived during the Late Triassic to Late Cretaceous epochs. It was named by paleontologist Adam M. Yates of the University of the Witwatersrand in 2007. Massopoda is a stem-based taxon, defined as all animals more closely related to Saltasaurus loricatus than to Plateosaurus engelhardti.

<span class="mw-page-title-main">Elliot Formation</span> Lithostratigraphic layer of the Stormberg Group in South Africa

The Elliot Formation is a geological formation and forms part of the Stormberg Group, the uppermost geological group that comprises the greater Karoo Supergroup. Outcrops of the Elliot Formation have been found in the northern Eastern Cape, southern Free State, and in the eastern KwaZulu-Natal provinces of South Africa. Outcrops and exposures are also found in several localities in Lesotho such as Qacha's Neck, Hill Top, Quthing, and near the capital, Maseru. The Elliot Formation is further divided into the lower (LEF) and upper (UEF) Elliot formations to differentiate significant sedimentological differences between these layers. The LEF is dominantly Late Triassic (Norian-Hettangian) in age while the UEF is mainly Early Jurassic (Sinemurian-Pliensbachian) and is tentatively regarded to preserve a continental record of the Triassic-Jurassic boundary in southern Africa. This geological formation is named after the town of Elliot in the Eastern Cape, and its stratotype locality is located on the Barkly Pass, 9 km north of the town.

Ignavusaurus is a genus of basal sauropodomorph dinosaur that lived during the Early Jurassic in what is now Lesotho. Its fossils were found in the Upper Elliot Formation which is probably Hettangian in age. It was described on the basis of a partial, well preserved articulated skeleton. The type species, I. rachelis, was described in 2010 by Spanish palaeontologist F. Knoll.

<i>Leyesaurus</i> Extinct genus of dinosaurs

Leyesaurus is an extinct genus of massospondylid sauropodomorph dinosaur known from the San Juan Province, northwestern Argentina.

<i>Meroktenos</i> Extinct genus of dinosaur from Triassic southern Africa

Meroktenos is a genus of basal sauropodomorph dinosaur that lived during the Late Triassic period of what is now Lesotho.

<i>Xingxiulong</i> Extinct genus of reptiles

Xingxiulong is a genus of bipedal sauropodiform from the Early Jurassic of China. It contains a single species, X. chengi, described by Wang et al. in 2017 from three specimens, two adults and an immature individual, that collectively constitute a mostly complete skeleton. Adults of the genus measured 4–5 metres (13–16 ft) long and 1–1.5 metres tall. Phylogenetic analysis suggests that Xingxiulong is most closely related to its contemporary Jingshanosaurus, although an alternative position outside of both the Sauropodiformes and Massospondylidae is also plausible.

Ingentia is a genus of early sauropod dinosaur from the Late Triassic of Argentina. The type specimen of Ingentia, PVSJ 1086, was discovered in the Quebrada del Barro Formation of northwestern Argentina. It was described in 2018 by Cecilia Apaldetti, Ricardo Nestor Martínez, Ignacio Alejandro Cerda, Diego Pol and Oscar Alcober who named the type and only species Ingentia prima, meaning "first huge one", as the taxon was one of the first very large sauropodomorphs to evolve, along with its close relative Lessemsaurus. A second specimen, PVSJ 1087, was referred, containing five tail vertebrae, both ulnae and radii, a left calfbone and a right foot.

<i>Ledumahadi</i> Sauropodomorph dinosaur genus from Early Jurassic South Africa

Ledumahadi is a genus of lessemsaurid sauropodomorph dinosaur from the Early Jurassic Elliot Formation in Free State Province, South Africa. The type and only species is L. mafube, known from a singular incomplete postcranial specimen. A quadruped, it was one of the first giant sauropodomorphs, reaching a weight of around 12 tonnes, despite not having evolved columnar limbs like its later huge relatives.

<i>Ngwevu</i> Sauropodomorph dinosaur genus from Early Jurassic South Africa

Ngwevu is a genus of massospondylid sauropodomorph dinosaur from the Lower Jurassic of South Africa. The genus contains one species, Ngwevu intloko.

References

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  3. 1 2 Pol, Diego; Otero, Alejandro; Apaldetti, Cecilia; Martínez, Ricardo N. (2021-01-11). "Triassic sauropodomorph dinosaurs from South America: The origin and diversification of dinosaur dominated herbivorous faunas". Journal of South American Earth Sciences. 107: 103145. Bibcode:2021JSAES.10703145P. doi:10.1016/j.jsames.2020.103145. ISSN   0895-9811. S2CID   233579282.
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