| Dinheirosaurus | |
|---|---|
 | |
| Articulated dorsal vertebrae in right view (1) proximal end of a dorsal rib in anterior view (2), and anterior caudal neural spine in posterior view (3). | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Clade: | Dinosauria |
| Clade: | Saurischia |
| Clade: | †Sauropodomorpha |
| Clade: | †Sauropoda |
| Superfamily: | †Diplodocoidea |
| Family: | †Diplodocidae |
| Genus: | †Dinheirosaurus Bonaparte &Mateus,1999 |
| Species: | †D. lourinhanensis |
| Binomial name | |
| †Dinheirosaurus lourinhanensis Bonaparte & Mateus, 1999 | |
| Synonyms | |
| |
Dinheirosaurus is agenus ofdiplodocidsauropod dinosaur that is known from fossils uncovered in modern-dayPortugal. It may represent a species ofSupersaurus.[1] The only species isDinheirosaurus lourinhanensis, first described byJosé Bonaparte andOctávio Mateus in 1999 forvertebrae and some other material from theLourinhã Formation. Although the precise age of the formation is not known, it can be dated around the earlyTithonian of theLate Jurassic.
The known material includes twocervical vertebrae, ninedorsal vertebrae, a fewribs, a fragment of apubis, and manygastroliths. Of the material, only the vertebrae are diagnostic, with the ribs and pubis being too fragmentary or general to distinguishDinheirosaurus. This material was first described as in the genusLourinhasaurus, but differences were noticed and in 1999 Bonaparte and Mateus redescribed the material under the newbinomialDinheirosaurus lourinhanensis. Another specimen, ML 418, thought to beDinheirosaurus, is now known to be from another Portuguese diplodocid. This means thatDinheirosaurus lived alongside manytheropods, sauropods,thyreophorans andornithopods, as well as at least one other diplodocid.
Dinheirosaurus is a diplodocid, a relative ofApatosaurus,Diplodocus,Barosaurus,Supersaurus, andTornieria. Among those, the closest relative toDinheirosaurus isSupersaurus.
ML 414 was first uncovered in 1987 by Mr. Carlos Anunciação. He was associated with theMuseu da Lourinhã, and after the excavations which lasted from the time of discovery until 1992,[2] the specimen was then moved into the museum, and catalogued under the number 414.[3] Dantaset al. preliminarily announced ML 414 as soon as the excavations were complete. To remove the fossils from the surrounding rock, a bulldozer and tilt hammer were needed. The fossils were situated at the top of a coastal cliff, and once removed, were shipped to Lourinhã in two blocks with the help of a crane. A year before being described as a new taxon, Dantaset al. assigned ML 414 toLourinhasaurus alenquerensis, previously grouped underApatosaurus.José Bonaparte andOctávio Mateus studied the material ofLourinhasaurus, concluding one specimen, under the name ML 414, to be more closely related to diplodocids of theMorrison Formation, and thus warranting a newbinomial name. This new species was described asDinheirosaurus lourinhanensis, with a full meaning of "Porto Dinheiro lizard fromLourinhã".[2][3]
Dinheirosaurus material includedvertebrae,ribs, partialpelvis, andgastroliths. The vertebrae were certainly from thecervical anddorsal regions, and are articulated. The two cervicals are not greatly preserved, although the twelve dorsals are articulated and in good condition. Other vertebral material includes seven centra that are fragmentary and a few neural arches, which are unattached. 12 dorsal ribs are preserved, as well as some appendicular elements.[2]David Weishampelet al. did not recognize all the material as belonging toDinheirosaurus, and only found 9 dorsals in the holotype, while also misinterpreting the pubis as a limb fragment. They also incorrectly stated that it was found in theCamadas de Alcobaça Formation.[4] Another pair of vertebrae, under collection number ML 418, was originally assigned toDinheirosaurus by Bonaparte and Mateus, but is now considered to be a distinct new unnamed genus of diplodocid.[3][5]
Dinheirosaurus was an average sized diplodocid, and had an elongated neck and tail.[4] The main features of the genus are based on its vertebral anatomy, and multiple vertebrae from across the spine have been found.[2] In total,Dinheirosaurus would have had an approximate length of 20–25 metres (66–82 ft) and weighed 8.8 metric tons (9.7 short tons).[6][7][8]
The animal is not known well from non-vertebral material, currently only consisting of partial ribs and a fragment of a pelvis. One of the ribs attached to the cervicals, and is quite fragmentary. It is elongated, although that might be a feature of distortion. Also undescribed by Bonaparte & Mateus are a set of thoracic ribs. Two ribs are from the left side of the animal. They are T-shaped in cross section, and display plesiomorphic features, although their incomplete state makes their identification uncertain. Multiple right ribs are preserved, including both the shafts and heads. They are similar to the left ribs, which also show that they lack pneumatization.[3] Other appendicular (non-vertebral) material includes a very incomplete and fragmentary shaft of the pubis, and over one hundredgastroliths. The pubis displays practically no anatomical features, and the gastroliths were not described in detail by Mannionet al. in 2012.[3]
The most distinguishing material ofDinheirosaurus comes from the vertebrae, which are well represented and described. Of the cervicals, only two of the assumed fifteen are preserved. According to Bonaparte & Mateus (1999), the cervicals would number 13 and 14. Apparently cervical 15 was lost during the excavation and removal of the holotype and only specimen ofDinheirosaurus. As of the original description, the thirteenth cervical was only prepared on the lateroventral portion. The length of the centrum is 71 cm (28 in), and the fourteenth cervical is quite similar overall. 63 cm (25 in) is the total measurement of the 14th cervical's centrum, which is well-preserved, complete, and concave along the bottom edge. Theneural spine, while compressed from above compared to the cervicals ofDiplodocus, is massive, and projects upwards towards its posterior end.[2]
A relatively complete series of dorsal vertebrae are known, which number one to seven. All of the dorsals, however, are distorted upwards due to their state of preservation. Bonaparte & Mateus (1999) noted that the position of the dorsals was not certain, and that in fact the first dorsal could have been the last cervical or even the second dorsal. A similar numbering was found inDiplodocus, with the first and second dorsals similar in anatomy to the last and second-last cervical. The dorsal vary in length from the 58 cm (23 in) of the first dorsal to the 25 cm (9.8 in) of the seventh, eight and ninth dorsals. Height in the vertebrae is also quite variable, with the shortest height being 51 cm (20 in) tall to 76 cm (30 in) tall, increasing from the first dorsal.[2]
Dinheirosaurus is not extremely well known, and as a consequence, itsphylogenetic position is not certain. In 2012 during a redescription of the taxon byPhilip Mannionet al., it was recovered, in bothcladograms, to be sister species toSupersaurus vivianae and together forming the mostbasaldiplodocines. A 2012 cladogram, published by Mannionet al. and using a modified matrix of Whitlock (2011) found thatDinheirosaurus was more primitive thanTorneria and more derived thanApatosaurus.[3] However, a cladogram from 2014 found that their group was supported, but in fact more primitive thanApatosaurus, and therefore outsideDiplodocinae.[9]In 2015,Dinheirosaurus lourinhanensis was considered a species ofSupersaurus in a new combinationS. lourinhanensis; their results are shown below.[1] However, to either confirm or refute this hypothesis, several remains of the holotype need to be prepared.[10]
| Diplodocidae |
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Previously,Dinheirosaurus was classified within a Diplodocidae excludingApatosaurus, for the differences anatomically are quite great. Bonaparte & Mateus found that a few features present suggested thatDinheirosaurus was more derived thanDiplodocus, butplesiomorphic features also present conclude that they branched separately andDinheirosaurus is not the descendant ofDiplodocus.[2] A 2004 study by Upchurchet al. found thatDinheirosaurus was an intermediate diplodocoid, along withCetiosauriscus,Amphicoelias, andLosillasaurus.[4]
As a diplodocid, it is probable thatDinheirosaurus possessed a whip-tail. If it did, it has been speculated that its tail could have been used like a bullwhip, with supersonic speed[11] or, more recently, as a tactile organ to keep in touch with other members of a group.[12] Being related to bothApatosaurus andDiplodocus,Dinheirosaurus probably possessed a squared snout. This means that it was probably a non-selective ground-feeding sauropod.[13]
Dinheirosaurus is one of relatively few sauropods for which gastroliths were found obviously alongside the type specimen. In 2007, an experiment usingDinheirosaurus,Diplodocus (=Seismosaurus), andCedarosaurus tested if sauropods used their gastroliths in anavian-stylegastric mill. The analysis took into account that among the hundreds of sauropods found, gastroliths are only known from a few associated specimens. Authors chose to use the three sauropods with the most associated gastroliths,Dinheirosaurus,Diplodocus, andCedarosaurus, because of the large amount of gastroliths found in birds. When birds were typically found to have 1.05% of their body weight gastroliths, the sauropodDiplodocus, which had the highest amount of gastroliths, only amassed to 0.03% body weight. This means that since the other sauropodsDinheirosaurus andCedarosaurus had less gastroliths to body mass, an avian-style gastric mill is unlikely to have evolved in sauropods, and they instead might have used gastroliths to absorb minerals.[14]
Dinheirosaurus was one of many dinosaurs to have lived in theLourinhã Formation during the Late Jurassic.[2] Manytheropods,sauropods, and especiallyornithischians are also from the Lourinhã Formation, which contains a similar fauna to theNorth American Morrison Formation.[4] Many theropods are known including an unnamed genus ofabelisaurid;[15] theallosauridAllosaurus fragilis[16]; theceratosauridCeratosaurus;[17][18] thecoelurosauriansAviatyrannis jurassica,[19] and cf.Richardoestesia; an intermediate theropod;[15] and themegalosauridTorvosaurus gurneyi.[19] Sauropods are less common, with only an intermediatediplodocid as well asDinheirosaurus;[3] thecamarasauridLourinhasaurus alenquerensis; theturiasaurZby atlanticus;[20] and thebrachiosauridLusotitan known.[21] Ornithischians are well represented, with identified remains persisting toTrimucrodon cuneatus;[22]Alocodon kuehnei;[23] thestegosauriansDacentrurus armatus,Miragaia longicollum,[24] andStegosaurus ungulatus;[25] theankylosauridDracopelta zbyszewskii;[26] theornithopodsDraconyx loureiroi,[27]Camptosaurus sp.,[20]Phyllodon henkelli,[23] and cf.Dryosaurus sp.[28]
Manyeusauropods, includingDinheirosaurus have been found in the Late Jurassic of Europe. The sauropods are from around the base of theTithonian as based on the presence ofAnchispirocyclina lusitanica. One sauropod, a diplodocid currently based on an unnamed specimen including vertebrae and some bones, is clearly different fromDinheirosaurus andLosillasaurus, confirming the presence of a least two and possibly more diplodocids in the Late Jurassic of Spain and Portugal. This is unique in the variety of diplodocoids in all Europe, with the only other genera possibly non-diplodocoid (Cetiosauriscus), or classified inRebbachisauridae. This suggests that the biogeography of primitive sauropods is incomplete, with possible primitive eusauropods and diplodocids surviving in the Late Jurassic, potentially until theBerriasian.[5]
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