| Lourinhasaurus | |
|---|---|
 | |
| Life reconstruction | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Clade: | Dinosauria |
| Clade: | Saurischia |
| Clade: | †Sauropodomorpha |
| Clade: | †Sauropoda |
| Clade: | †Macronaria |
| Family: | †Camarasauridae |
| Genus: | †Lourinhasaurus Dantas et al., 1998 |
| Species: | †L. alenquerensis |
| Binomial name | |
| †Lourinhasaurus alenquerensis (Lapparent & Zbyszewski, 1957) | |
| Synonyms | |
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Lourinhasaurus is an extinct genus of herbivoroussauropoddinosaur dating fromLate Jurassic strata ofEstremadura,Portugal. The genus ismonotypic, containing one species,Lourinhasaurus alenquerensis. The type specimen for this species was discovered near the town ofAlenquer, near an abandoned mill.[1][2] The specimen is housed at the Geological Museum of Lisbon. The research history ofLourinhasaurus is not without controversies, with referred specimens later being interpreted as not belonging to thegenus (such as thetype specimen ofSupersaurus (=Dinheirosaurus) lourinhanensis).Lourinhasaurus means "lizard fromLourinhã" literally translated, despite the fact that the type specimen wasn't found in theLourinhã municipality.
In June 1949 a partial skeleton of a large sauropod, found by American geologist Harold Weston Robbins, was excavated in a locality nearAlenquer.[3][1] The excavations at the locality, thereafter referred to as Moinho do Carmo quarry,[2] were conducted by the geological Services of Portugal under the direction ofGeorges Zbyszewski.[1] The locality lies within the Sobral Formation (a lateral equivalent to the Porto Novo and Praia Azul Members of theLourinhã Formation), a sequence of rocks deposited in aestuarine delta complex context, dated from the earlyTithonian.[2] The specimen, which preserved more than 26 vertebrae, dorsal ribs and much of the appendicular skeleton (minus the hands and feet), probably represents a single individual and constitutes the most complete sauropod skeleton found in Portugal thus far.[2] In 1957,Albert-Félix de Lapparent and Georges Zbyszewski published their work on the Portuguese vertebrate fauna, "Les dinosauriens du Portugal", wherein they erected a newApatosaurus species,Apatosaurus alenquerensis, based on the Moinho do Carmo specimen, as well as well as on a caudal vertebrae series found at S. Bernardino (Peniche), and other fragmentary specimens. Thespecific namealenquerensis refers to the locality ofAlenquer.[1]
In 1983, another partial skeleton of a sauropod dinosaur was discovered at the Porto Dinheiro (Lourinhã). The skeleton was excavated in 1987, 1991 and 1992 by members of theLourinhã Museum, theNational Museum of Natural History and Science, Lisbon and theUniversity of Salamanca. It was discovered in layers of the Praia da Amoreira-Porto Novo Member of theLourinhã Formation, dated from the lateKimmeridgian, and therefore slightly older than the Moinho do Carmo specimen.The skeleton is composed of nine neural spines, 12 complete posterior cervical and dorsal vertebrae, 12 dorsal ribs from both sides of the animal and other fragmentary material from the appendicular skeleton. Furthermore, one tooth andgastroliths were found in association with the specimen.[4][5] In 1998,Pedro Dantas and colleagues publish their work on the Porto Dinheiro specimen, that they interpreted as being the same species as the Moinho do Carmo specimen. They proposed thecombinatio novaLourinhasaurus alenquerensis, and emended the diagnosis for the taxon,[5] although mostly based on the Porto Dinheiro specimen.[2] They did not appoint a type specimen.[6] The new generic name refers to the locality of the Porto Dinheiro specimen, which lies within theLourinhã municipality.[5] Just a year later, however, the Porto Dinheiro specimen was reinterpreted as adiplodocid, and given the new nameDinheirosaurus lourinhanensis. The authors of this work still suggested the Moinho do Carmo specimen represented a new species[7]
It was not until 2003 that the Moinho do Carmo specimen was appointed as thelectotype forLourinhasaurus alenquerensis.[6] In 2014, Mocho and colleagues published a complete re-description of the Moinho do Carmo specimen, including elements never described before, and also provided a phylogenetic revision ofLourinhasaurus. They recoveredLourinhasaurus alenquerensis as a valid genus, closely related toCamarasaurus, a sauropod genus from theLate JurassicMorrisson Formation.[2] The other partial specimens thatAlbert-Félix de Lapparent and Georges Zbyszewski referred toApatosaurus alenquerensis, such as the caudal vertebrae series from São Bernardino, are no longer attributed toLourinhasaurus alenquerensis, instead being considered indeterminate remains.[8]
Lourinhasaurus alenquerensis is a large herbivorous dinosaur, closely related toCamarasaurus.[2][9][10][11] It possesses some notable features in its skeleton, such as a ventral concavity in the anterior-to-middle dorsal vertebrae, very tall sacral neural spines, a posteriorly-oriented postacetabular process of the ilium, tibiae and fibulae of equal length, and a marked lateral deflection of the femoral shaft (without the lateral bulge commonly seen intitanosaurs), among others.[2] The higher humerus/femur length ratio ofLourinhasaurus, as pointed out byJohn Stanton McIntosh, might have suggested a slightly more verticalized posture compared toCamarasaurus.[2][9][10]Gregory S. Paul suggestedLourinhasaurus alenquerensis measured 18 metres (59 ft) in length and weighed around 5 metric tons (5.5 short tons).[12]
Upon its original description, the Moinho do Carmo specimen was considered a species ofApatosaurus.[1] The attribution of this species toApatosaurus was subsequently questioned. In 1970 Rodney Steel renamed itAtlantosaurus alenquerensis,[13] and in 1978 George Olshevsky coined proposed the nameBrontosaurus alenquerensis.[14] Notably, John Stanton McIntosh in 1990 proposed for the first time that the Moinho do Carmo specimen represented a new species with close affinity toCamarasaurus. He published a new taxonomic framework for the skeleton, basing his assertion on the opisthocoelic dorsal vertebrae, the broadly expanded distal scapular blade, the long and slender humerus, and the unexpanded distal ends of the ischia that the specimen shares withCamarasaurus. The authors proposedCamarasaurus alenquerensis as a provisory assignation for the specimen.[9][10][11] McIntosh later suggested the possibility that the skeleton might represent its owngenus, based on the higher humerus/femur length ratio compared toCamarasaurus.[10][11] In the following years,Lourinhasaurus had been considered a basaleusauropod,[15] a non-macronarianneosauropod,[16][17] a basalmacronarian,[18][19] and even a form related toLaurasiaformes.[20][21]
It wasn't until 2014, with the full re-description of the specimen published by Mocho and colleagues, that the phylogenetic relationships of the specimen were cleared out. The phylogenetic hypotheses proposed by that work suggest thatLourinhasaurus is a basal member of theMacronaria closely related toCamarasaurus, in agreement with McIntosh's earlier views. This study recovered, for the first time in a cladistic analysis,Camarasauridae as a monophyletic clade, includingCamarasaurus,Lourinhasaurus andTehuelchesaurus.[2]
Mocho et al. 2014 strict consensus cladogram obtained from Wilson’s (2002) data matrix.[2]
