Aigialosauridae

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Aigialosauridae
Temporal range: Cenomanian, 99.7–94.3  Ma
Aigialosaurus bucchichi skull.jpg
Skull of Opetiosaurus
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Clade: Mosasauria
Superfamily: Mosasauroidea
Family: Aigialosauridae
Kramberger, 1892
Genera

Aigialosauridae (from Greek, aigialos, meaning "seashore", and sauros, "lizard") is a family of Late Cretaceous semiaquatic pythonomorph lizards closely related to the mosasaurs. Regarded by some paleontologists as a distinct monophyletic group and by others as an adaptive grade within the basal mosasauroids, recent molecular and morphological data suggests that they are the oldest known members of the lineage leading to the mosasaurs. [1]

Contents

The family is recognized as containing two species, normally classified into two genera; Aigialosaurus and Opetiosaurus . When used as an adaptive grade rather than as an actual monophyletic group, many other basal mosasauroids of uncertain affinities are occasionally referred to as "aigialosaurs", such as the genera Komensaurus , Haasiasaurus , Carsosaurus and Dallasaurus and even entire mosasaur clades, such as the Tethysaurinae. [2] The term "plesiopedal mosasaurs" or "mosasaurs with a plesiopedal limb condition" is a more formal way to refer to such primitive species firmly within the family Mosasauridae. [3]

Description

Life restoration of Aigialosaurus dalmaticus. Aigialosaurus dalmaticus.jpg
Life restoration of Aigialosaurus dalmaticus.

Aigialosaurids were semi-aquatic lizards that inhabited shallow marine environments in the ancient Tethys Ocean, the only known fossils having been recovered from Croatia. Their skulls are similar to the skulls of more derived mosasaurs, though the postcranial skeleton is far more similar to that of terrestrial lizards. [4]

Classification

The systematics and taxonomy of the Aigialosauridae is controversial and has a problematic history. [5] Despite thorough reviews of the relationships between early Mosasauroidea and redescriptions of the two normally recognized aigialosaurid genera, Aigialosaurus [6] and Opetiosaurus, [7] the status of the family remains uncertain.

Dutchak & Caldwell (2009) designated Opetiosaurus as a junior synonym of Aigialosaurus (as Aigialosaurus bucchichi), [7] which suggested a very close relationship between the two. Their own analysis does not strictly support such a conclusion, [5] and neither do subsequent analyses. Indeed, analyses done by Madzia & Cau (2017) show that the two genera are not necessarily more closely related to each other than either is to more derived mosasauroids, suggesting not only that Opetiosaurus is a valid genus, but also calling the validity of the Aigialosauridae as a monophyletic group into question. [5]

Related Research Articles

<span class="mw-page-title-main">Mosasaur</span> Extinct marine lizards of the Late Cretaceous

Mosasaurs are an extinct group of large aquatic reptiles within the family Mosasauridae that lived during the Late Cretaceous. Their first fossil remains were discovered in a limestone quarry at Maastricht on the Meuse in 1764. They belong to the order Squamata, which includes lizards and snakes.

Tylosaurus is a genus of mosasaur, a large, predatory marine reptile closely related to modern monitor lizards and to snakes, from the Late Cretaceous.

<span class="mw-page-title-main">Halisaurinae</span> Extinct subfamily of lizards

The Halisaurinae are a subfamily of mosasaurs, a group of Late Cretaceous marine lizards. They were small to medium-sized, ranging from just under 3 meters in Eonatator sternbergi to as much as 8 or 9 meters in Pluridens serpentis. They tended to have relatively slender jaws and small, numerous teeth, suggesting a diet of small fish and other prey. Although the skeleton is primitive compared to other Mosasauridae in many respects, halisaurines had the distinctive hypocercal tail of other mosasaurids suggesting good swimming ability, and they persisted alongside other mosasaurs until the end of the Cretaceous. The earliest known remains of halisaurines occur in rocks of Santonian age and the subfamily persists until the latest Maastrichtian. Halisaurines are known from North and South America, Europe, Asia and Africa, indicating a more or less global distribution in the Late Cretaceous. Four genera are currently recognized: Eonatator, Halisaurus, Phosphorosaurus and Pluridens.

<span class="mw-page-title-main">Pythonomorpha</span> Clade of lizards

Pythonomorpha was originally proposed by paleontologist Edward Drinker Cope (1869) as a reptilian order comprising mosasaurs, which he believed to be close relatives of Ophidia (snakes). The etymology of the term Pythonomorpha comes from the Greek Python and morphe ("form"), and refers to the generally serpentine body plan of members of the group. Cope wrote, "In the mosasauroids, we almost realize the fictions of snake-like dragons and sea-serpents, in which men have been ever prone to indulge. On account of the ophidian part of their affinities, I have called this order Pythonomorpha." Cope incorporated two families, the Clidastidae and the Mosasauridae.

<i>Globidens</i> Extinct genus of lizards

Globidens is an extinct genus of mosasaurid oceanic lizard classified as part of the Globidensini tribe in the Mosasaurinae subfamily.

<i>Prognathodon</i> Extinct genus of lizards

Prognathodon is an extinct genus of marine lizard belonging to the mosasaur family. It is classified as part of the Mosasaurinae subfamily, alongside genera like Mosasaurus and Clidastes. Prognathodon has been recovered from deposits ranging in age from the Campanian to the Maastrichtian in the Middle East, Europe, New Zealand, and North America.

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

Dallasaurus is a basal mosasauroid from the Upper Cretaceous of North America. Along with Russellosaurus, Dallasaurus is one of the two oldest mosasauroid taxa currently known from North America. It is also one of the smallest known mosasaurines, measuring approximately 1 m (3.3 ft) in length.

<span class="mw-page-title-main">Mosasauroidea</span> Extinct marine lizards of the Late Cretaceous

Mosasauroidea is a superfamily of extinct marine lizards that existed during the Late Cretaceous. Basal members of this group consist of small semiaquatic forms with terrestrial limbs ("plesiopedal"), while laters members include larger fully aquatic paddle-limbed ("hydropedal") forms commonly known as mosasaurs. These were traditionally grouped within their own separate families, the Aigialosauridae and Mosasauridae respectively. However, phylogenetic studies have since found plesiopedal mosasauroids to be a non-monophyletic group, with some taxa nestled within the mosasaurids.

<i>Tethysaurus</i> Extinct genus of lizards

Tethysaurus is an extinct genus of tethysaurine mosasauroid from the Early Turonian period. The only species is Tethysaurus nopcsai.

<i>Angolasaurus</i> Extinct genus of lizards

Angolasaurus is an extinct genus of mosasaur. Definite remains from this genus have been recovered from the Turonian and Coniacian of Angola, and possibly the Coniacian of the United States, the Turonian of Brazil, and the Maastrichtian of Niger. While at one point considered a species of Platecarpus, recent phylogenetic analyses have placed it between the (then) plioplatecarpines Ectenosaurus and Selmasaurus, maintaining a basal position within the plioplatecarpinae.

<i>Aigialosaurus</i> Extinct genus of lizards

Aigialosaurus is an extinct genus of Late Cretaceous marine or semiaquatic lizard classified as part of the family Aigialosauridae within the Mosasauroidea. Exclusively found in deposits of Cenomanian age near Hvar, Croatia, the genus contains one valid species, A. dalmaticus. According to recent molecular and morphological data, Aigialosaurus is the oldest known member of the lineage leading to large Cretaceous marine reptiles called mosasaurs, a group most closely related to snakes among living squamates. It was a relatively small reptile with a complete specimen measuring 65 cm (2.13 ft) long.

<i>Opetiosaurus</i> Extinct genus of lizards

Opetiosaurus is an extinct genus of Late Cretaceous marine or semiaquatic lizard classified as part of the family Aigialosauridae within the Mosasauroidea. Exclusively found in deposits of Cenomanian age near Hvar, Croatia, the genus contain one valid species, O. bucchichi. It was a small reptile measuring 1 metre (3.3 ft) long.

<span class="mw-page-title-main">Mosasaurini</span> Extinct tribe of lizards

Mosasaurini is an extinct tribe of mosasaurine mosasaurs who lived during the Late Cretaceous and whose fossils have been found in North America, South America, Europe, Africa and Oceania, with questionable occurrences in Asia. They are highly derived mosasaurs, containing genera like Plotosaurus, having unique adaptations to fast swimming speeds, or Mosasaurus, which is among the largest known marine reptiles.

Eremiasaurus is a genus of mosasaurs, an extinct group of marine reptiles. It lived during the Maastrichtian stage of the Late Cretaceous in what is now North Africa. Only one species is known, E. heterodontus, described in 2012 from two remarkably complete fossil specimens discovered in the Ouled Abdoun Basin, Morocco. This site is known to have delivered a significant number of other related mosasaurs.

<span class="mw-page-title-main">Tethysaurinae</span> Extinct subfamily of lizards

The Tethysaurinae are a subfamily of mosasaurs, a diverse group of Late Cretaceous marine squamates. Members of the subfamily are informally and collectively known as "tethysaurines" and have been recovered from North America and Africa. Only two tethysaurine genera are known, Pannoniasaurus and Tethysaurus. The genera Yaguarasaurus and Russellosaurus were previously considered tethysaurines until they were grouped with Romeosaurus in the new subfamily Yaguarasaurinae. A possible member of this clade (subfamily) is a mosasaur specimen known from a maxilla fragment, found in 1960 in the Czech Republic, in Dolní Újezd near Litomyšl.

<span class="mw-page-title-main">Timeline of mosasaur research</span>

This timeline of mosasaur research is a chronologically ordered list of important fossil discoveries, controversies of interpretation, and taxonomic revisions of mosasaurs, a group of giant marine lizards that lived during the Late Cretaceous Epoch. Although mosasaurs went extinct millions of years before humans evolved, humans have coexisted with mosasaur fossils for millennia. Before the development of paleontology as a formal science, these remains would have been interpreted through a mythological lens. Myths about warfare between serpentine water monsters and aerial thunderbirds told by the Native Americans of the modern western United States may have been influenced by observations of mosasaur fossils and their co-occurrence with creatures like Pteranodon and Hesperornis.

<span class="mw-page-title-main">Globidensini</span> Tribe of lizards

The Globidensini or Globidentatini are a tribe of mosasaurine mosasaurs, a diverse group of Late Cretaceous marine squamates. Members of the tribe, known as "globidensins" or "globidensine mosasaurs", have been recovered from North America, Europe, Africa and Asia. The tribe contains the genera Globidens, Carinodens, Igdamanosaurus, Harranasaurus and Xenodens. Features of the maxilla and digits make the placement of Carinodens and Xenodens in the tribe uncertain; some researchers have suggested that they may be more appropriately placed in the Mosasaurini.

<span class="mw-page-title-main">Dolichosauridae</span> Extinct family of lizards

Dolichosauridae is a family of Cretaceous aquatic lizards. They are widely considered to be the earliest and most primitive members of Mosasauria, though some researchers have recovered them as more closely related to snakes.

References

  1. Wilf, P.; Reeder, T. W.; Townsend, T. M.; Mulcahy, D. G.; Noonan, B. P.; Wood, P. L.; Sites, J. W.; Wiens, J. J. (2015). "Integrated Analyses Resolve Conflicts over Squamate Reptile Phylogeny and Reveal Unexpected Placements for Fossil Taxa". PLOS ONE. 10 (3): e0118199. Bibcode:2015PLoSO..1018199R. doi: 10.1371/journal.pone.0118199 . PMC   4372529 . PMID   25803280.
  2. Makádi, László; Caldwell, Michael W.; Ősi, Attila (2012-12-19). "The First Freshwater Mosasauroid (Upper Cretaceous, Hungary) and a New Clade of Basal Mosasauroids". PLOS ONE. 7 (12): e51781. Bibcode:2012PLoSO...751781M. doi: 10.1371/journal.pone.0051781 . ISSN   1932-6203. PMC   3526648 . PMID   23284766.
  3. Bell, G.L.; Polcyn, M.J. (2005). "Dallasaurus turneri, a new primitive mosasauroid from the Middle Turonian of Texas and comments on the phylogeny of Mosasauridae (Squamata)". Netherlands Journal of Geosciences. 84 (3): 177–194. Bibcode:2005NJGeo..84..177B. doi: 10.1017/s0016774600020965 . S2CID   17551989.
  4. Dutchak, A.R. (2005). "A review of the taxonomy and systematics of aigialosaurs". Netherlands Journal of Geosciences. 84 (3): 221–229. Bibcode:2005NJGeo..84..221D. doi: 10.1017/S0016774600021004 . S2CID   133058224.
  5. 1 2 3 Madzia, Daniel; Cau, Andrea (2017). "Inferring 'weak spots' in phylogenetic trees: application to mosasauroid nomenclature". PeerJ. 5: e3782. doi: 10.7717/peerj.3782 . PMC   5602675 . PMID   28929018.
  6. Dutchak, Alex R; Caldwell, Michael W (2006-12-01). "Redescription of Aigialosaurus dalmaticus Kramberger, 1892, a Cenomanian mosasauroid lizard from Hvar Island, Croatia". Canadian Journal of Earth Sciences. 43 (12): 1821–1834. Bibcode:2006CaJES..43.1821D. doi:10.1139/e06-086. ISSN   0008-4077.
  7. 1 2 Dutchak, Alex R.; Caldwell, Michael W. (2009-06-12). "A redescription of Aigialosaurus (= Opetiosaurus) bucchichi (Kornhuber, 1901) (Squamata: Aigialosauridae) with comments on mosasauroid systematics". Journal of Vertebrate Paleontology. 29 (2): 437–452. Bibcode:2009JVPal..29..437D. doi:10.1671/039.029.0206. ISSN   0272-4634. S2CID   86140123.