Pterodaustro

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Pterodaustro
Temporal range:
Ma
↓
Cast of a fossil specimen at the
Museo Argentino de Ciencias Naturales
in Caballito, Buenos Aires, Argentina
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Order: †Pterosauria
Suborder: †Pterodactyloidea
Family: †Ctenochasmatidae
Subfamily: †
Ctenochasmatinae
Tribe: †
Pterodaustrini
Genus: †Pterodaustro
Bonaparte, 1970
Species:
†P. guinazui
Binomial name
†Pterodaustro guinazui
Bonaparte, 1970
Synonyms

Pterodaustro is a

ctenochasmatid pterodactyloid pterosaur from South America. Its fossil remains dated back to the Early Cretaceous
period, about 105 million years ago.

Discovery and naming

Fossil cast, Muséum national d'Histoire naturelle, Paris

The first fossils, among them the holotype PVL 2571, a thigh bone, were discovered during the late 1960s by José Bonaparte in the Lagarcito Formation, situated in the San Luis Province of Argentina, and dating from the Albian. The genus has later also been found in Chile in the Santa Ana Formation.[citation needed] At the Argentine site, the just 50 square meters (540 sq ft) large "Loma del Pterodaustro", since then, during several expeditions, over 750 Pterodaustro specimens have been collected, 288 of them having been catalogued until 2008. This makes the species one of the best known pterosaurs, with examples from all growth stages, from egg to adult.

The genus was named in 1969 by

paleontologist Román Guiñazú. It was amended in 1978 by Peter Wellnhofer into guinazui, because diacritical signs such as the tilde
are not allowed in specific names.

Description

Restored skull

Pterodaustro has a very elongated skull, up to 29 centimeters (11 in) long. The portion in front of the eye sockets comprises 85 percent of skull length. The long snout and lower jaws curve strongly upwards; the

dentine and a pulp. Despite being made of very hard material, they might still have been flexible to some extent due to their extreme length-width ratio, a bend of up to 45 degrees being possible.[4]
The upper jaws also carried teeth, but these were very small with a flat conical base and a spatula-formed crown. These teeth also do not have separate tooth sockets but were apparently held by ligaments in a special tooth pad, that was also covered with small ossicles, or bone plates.

The back of the skull was also rather elongated and in a low position; there are some indications for a low parietal crest.

Pterodaustro had a maximum adult wingspan of approximately 3 m (9.8 ft) and a maximum body mass of approximately 9.2 kg (20 lb).[5] Its hindlimbs are rather robust and its feet large. Its tail is uniquely elongated for a pterodactyloid, containing twenty-two caudal vertebrae, whereas other members of this group have at most, sixteen.

Paleobiology

Life restoration

Pterodaustro probably strained food with its tooth comb, a method called "filter feeding", also practised by modern

flamingos.[6] Once it caught its food, Pterodaustro probably mashed it with the small, globular teeth present in its upper jaw. Like other ctenochasmatoids, Pterodaustro has a long torso and proportionally massive and splayed hindfeet, adaptations for swimming.[7]

Robert Bakker suggested that, like flamingos, this pterosaur's diet may have resulted in a pink hue.[8]

At least two specimens of Pterodaustro have been found, MIC V263 and MIC V243, with

gizzard stones in the stomach cavity, the first ever reported for any pterosaur. These clusters of small stones with angled edges support the idea that Pterodaustro ate mainly small, hard-shelled aquatic crustaceans using filter-feeding. Such invertebrates are abundant in the sediment of the fossil site.[9]

A study of the growth stages of Pterodaustro concluded that juveniles grew relatively fast in their first two years, attaining about half of the adult size. Then they reached sexual maturity, growing at a slower rate for four to five years until there was a determinate growth stop.[10]

In 2004 a Pterodaustro embryo in an egg was reported, specimen MHIN-UNSL-GEO-V246. The egg was elongated, 6 centimeters (2.4 in) long and 22 millimeters (0.87 in) across, and its mainly flexible shell was covered with a thin layer of calcite, 0.3 millimeters thick.[11] Three-dimensionally preserved eggs were reported in 2014.[12]

Comparisons between the

nocturnal and similar in activity patterns to modern anseriform birds that feed at night,[13] although method of this research is questioned by some researchers.[14]

Because of its long torso and neck and comparatively short legs, Pterodaustro was unique among pterosaurs in having difficulties to launch. Even with the pterosaurian quadrupedal launching mechanism, it would have required frantic and fairly-low angled take-offs possible only in open areas, much like modern

geese and swans.[7]

Phylogeny

Bonaparte in 1970 assigned Pterodaustro to the

cladistic studies by Alexander Kellner and David Unwin have shown a position within the family Ctenochasmatidae, together with other filter feeders.[7]

Skeletal restoration

In 2018, a topology by Longrich, Martill and Andres recovered Pterodaustro within the family

Pterodaustrini, in a more basal position than Beipiaopterus and Gegepterus.[15]

Ctenochasmatidae

See also

References

  1. ^ L. Codorniú and Z. Gasparini. 2007. Pterosauria. In Z. Gasparini, L. Salgado, R. A. Coria (eds.), Patagonian Mesozoic Reptiles. Indiana University Press, Bloomington, IN 143-166.
  2. ^ Bonaparte, J. F. (1970). "Pterodaustro guinazui gen. et sp. nov. Pterosaurio de la Formacion Lagarcito, Provincia de San Luis, Argentina y su significado en la geologia regional (Pterodactylidae)". Acta Geologica Lilloana. 10: 209–225.
  3. ISBN 0-7607-0154-7
    .
  4. PMID 10562511
    .
  5. PMID 34294737
    .
  6. ISBN 1-84028-152-9
    .
  7. ^
    ISBN 0691150613
    .
  8. ISBN 978-0-7525-3166-3.[page needed
    ]
  9. ^ Codorniú, L., Chiappe, L.M., Arcucci, A., and Ortiz-Suarez, A. (2009). "First occurrence of gastroliths in Pterosauria (Early Cretaceous, Argentina)". XXIV Jornadas Argentinas de Paleontología de Vertebrados
  10. PMID 18308672.{{cite journal}}: CS1 maint: multiple names: authors list (link
    )
  11. S2CID 4396534.{{cite journal}}: CS1 maint: multiple names: authors list (link
    )
  12. hdl:11336/6990
    .
  13. S2CID 33253407
    .
  14. ISSN 0036-8075
    .
  15. ^ Longrich, N.R., Martill, D.M., and Andres, B. (2018). Late Maastrichtian pterosaurs from North Africa and mass extinction of Pterosauria at the Cretaceous-Paleogene boundary. PLoS Biology, 16(3): e2001663.
    doi:10.1371/journal.pbio.2001663

External links
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