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Lusitanosaurus

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Extinct genus of dinosaur

Lusitanosaurus
Temporal range: Late Sinemurian 191 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Clade: Archosauromorpha
Genus: †Lusitanosaurus
Species: †L. liasicus
Binomial name
†Lusitanosaurus liasicus
Lapparent & Zbyszewski, 1957

Lusitanosaurus (meaning "Portuguese lizard") is a genus of reptile from the Sinemurian stage of Early Jurassic of Portugal, maybe from the Coimbra Formation. It was considered the second example of the Dinosaurian group Thyreophora from the Sinemurian of Europe and it the oldest known dinosaur from the Iberian Peninsula, but this affinity has been contested. It is based on a large left maxilla with teeth that was lost in the fire at Museu Nacional de História Natural e da Ciência, Lisbon, in 1978.

Description

The fossil consists of a single partial left maxilla, an upper jaw bone, with seven teeth. The jaw measured 10.5 cm, with an estimated skull of 38.7 cm for the living animal. The teeth were described to be similar to those of Scelidosaurus, which approaches it narrowly by the presence of important anterior and posterior basilar points on each tooth. The maxilla was clearly bigger, being the double of the size than the maxilla of Scelidosaurus. Lapparent & Zbyszewski vinculated it originally with Scelidosaurus and assigned the two to Stegosauria, he described that the teeth present were different to Scelidosaurus. Ginsburg cited the specimen and note a bigger size than the holotype of Scelidosaurus.

History of discovery

Lusitanosaurus restored as a thyreophoran as originally described

The genus was first described by Albert-Félix de Lapparent and Georges Zbyszewski in 1957. The type species is Lusitanosaurus liasicus. The generic name is derived from Lusitania, the ancient Latin name for the region. The specific name refers to the Lias. The holotype was part of the collection of the Museu de História Natural da Universidade de Lisboa. The exact location of the find and the date of collection are unknown, which makes a correct geological dating difficult, but it can be inferred from the matrix rock that it has been discovered near São Pedro de Moel, in strata from the Late Sinemurian (Early Jurassic). This would make it the oldest known dinosaur from Portugal.

Classification

It was originally assigned to the Stegosauria by de Lapparent, Lusitanosaurus was then considered a basal member of the Thyreophora, perhaps belonging to the Scelidosauridae, but this is tentative, as this family is considered paraphyletic. The fragmentary condition of the specimen does not help to identify it well, as it can be from different grades inside basal Thyreophora, such as a relative of Emausaurus. Some authors consider it a nomen dubium.

A revision of the phylogenetic relationships of early-diverging ornithischians found that the material of Lusitanosaurus as figured and described does not show any features characteristic of Thyreophora or even Ornithischia, and instead displays several differences that are found in the groups Pterosauria, Squamata, Tanystropheidae and basal Cynodontia. The presence of ankylothecodont teeth supported a placement of Lusitanosaurus preliminarily within Archosauromorpha, but not as an ornithischian.

Paleoenvironment

The São Pedro de Moel rocks consists on calcareous strata, mostly from Marginal Marine environments belonging to the Coimbra Formation. Outside Lusitanosaurus, fishes have been found on this rock, such as members of the genus Proleptolepis. Ammonites are also common, such as Oxynoticeras, Bifericeras, Cheltonia and Plesechioceras. Finally, this section is known for its calcareous nannofossils that expose the Sinemurian/Pliensbachian transition more detailed than in any part of Portugal.

References

  1. Costa, Francisco; Mateus, Octávio (2019-11-13). "Dacentrurine stegosaurs (Dinosauria): A new specimen of Miragaia longicollum from the Late Jurassic of Portugal resolves taxonomical validity and shows the occurrence of the clade in North America". PLOS ONE. 14 (11): e0224263. Bibcode:2019PLoSO..1424263C. doi:10.1371/journal.pone.0224263. ISSN 1932-6203. PMC 6853308. PMID 31721771.
  2. Ginsburg (1964): Discovery of a scelidosaurian (ornithischian dinosaur) in the Upper Triassic of Basutoland. C. R. Acad. Sc. Paris, vol. 258 (24 February 1964). Group 9.
  3. A.F. de Lapparent & G. Zbyszewski, 1957, "Les dinosauriens du Portugal", Mémoires des Services Géologiques du Portugal, nouvelle série 2: 1-63
  4. Duarte, L. V., & Soares, A. F. (2002). Litostratigrafia das séries margo-calcárias do Jurássico inferior da Bacia Lusitânica (Portugal).
  5. Antunes, Miguel Telles; Mateus, Octávio (2003). "Dinosaurs of Portugal". Comptes Rendus Palevol. 2 (1): 77–95. Bibcode:2003CRPal...2...77A. doi:10.1016/s1631-0683(03)00003-4. ISSN 1631-0683.
  6. Mateus, O. (2019). Notes and review of the ornithischian dinosaurs of Portugal. Journal of Vertebrate Paleontology, 27.
  7. Fonseca, A.O.; Reid, I.J.; Venner, A.; Duncan, R.J.; Garcia, M.S.; Müller, R.T. (2024). "A comprehensive phylogenetic analysis on early ornithischian evolution". Journal of Systematic Palaeontology. 22 (1): 2346577. Bibcode:2024JSPal..2246577F. doi:10.1080/14772019.2024.2346577.
  8. Correia, G. G.; Duarte, L. V.; Pereira, A.; Silva, R. L. (2013-02-15). "Outcrop gamma-ray spectrometry: Applications to the Sinemurian–Pliensbachian organic-rich facies of the Lusitanian Basin (Portugal)". Journal of Iberian Geology. 38 (2). doi:10.5209/rev_jige.2012.v38.n2.40464. ISSN 1886-7995.
  9. M. T. Antunes, R. B. Rocha, and S. Wenz. 1981. Faunule ichthyologique du Lias inférieur de S. Pedro de Muel, Portugal. Ciências da Terra (UNL) 6:101-116
  10. COMAS-RENGIFO, María José; GOY, Antonio; PIÑUELA, Laura; GARCÍA-RAMOS, José Carlos; SUÁREZ VEGA, Luis Carlos; PAREDES, Ricardo (2021-03-12). "El Sinemuriense superior: cronozonas Obtusum y Oxynotum en Asturias, España. Ammonoideos y correlación con otras cuencas del oeste de Europa". Spanish Journal of Palaeontology. 36 (1): 19–50. doi:10.7203/sjp.36.1.20306. ISSN 2660-9568.
  11. Plancq, J.; Mattioli, E.; Pittet, B.; Baudin, F.; Duarte, L.V.; Boussaha, M.; Grossi, V. (2016). "A calcareous nannofossil and organic geochemical study of marine palaeoenvironmental changes across the Sinemurian/Pliensbachian (early Jurassic, ~ 191 Ma) in Portugal". Palaeogeography, Palaeoclimatology, Palaeoecology. 449: 1–12. Bibcode:2016PPP...449....1P. doi:10.1016/j.palaeo.2016.02.009. ISSN 0031-0182.

External links

  • Antunes, M.T. & Mateus, O. (2003). Dinosaurs of Portugal. C. R. Palevol, 2: 77–95.
  • Lusitanosaurus in the Paleobiology Database
Taxon identifiers
Lusitanosaurus
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