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] They defined Aigialosauridae as "the most inclusive clade containing Aigialosaurus dalmaticus and Opetiosaurus bucchichi , but not Dolichosaurus longicollis , Adriosaurus suessi , Pontosaurus lesinensis , or the clade originating with the most recent common ancestor of Halisaurus platyspondylus , Mosasaurus hoffmannii , and Tylosaurus proriger ". This definition highlights the instability of "aigialosaur" phylogeny and ensures that the name Aigialosauridae is only used in the cases when Aigialosaurus dalmaticus and Opetiosaurus bucchichi form a clade to exclusion of more derived mosasauroids. [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 russellosaurine mosasaur that lived about 92 to 66 million years ago during the Turonian to Maastrichtian stages of the Late Cretaceous. Its fossils have been found primarily around North Atlantic Ocean including in North America, Europe, and Africa.

Plioplatecarpinae is a subfamily of mosasaurs, a diverse group of Late Cretaceous marine squamates. Members of the subfamily are informally and collectively known as "plioplatecarpines" and have been recovered from all continents, though the occurrences in Australia remain questionable. The subfamily includes the genera Latoplatecarpus, Platecarpus, Plioplatecarpus and Plesioplatecarpus.

<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.

<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>Halisaurus</i> Extinct genus of lizards

Halisaurus is an extinct genus of mosasaur named by Othniel Charles Marsh in 1869. The holotype, consisting of an angular and a basicranium fragment discovered near Hornerstown, New Jersey, already revealed a relatively unique combination of features and prompted a new genus to be described. Its name is a portmanteau of the Ancient Greek ἅλς and σαῦρος. It was renamed by Marsh to Baptosaurus in 1870, since he believed the name to already be preoccupied by the fish Halosaurus. According to modern rules, a difference of a letter is enough and the substitute name is unneeded, making "Baptosaurus" a junior synonym.

<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. Daniel Madzia and Andrea Cau in 2017 defined Mosasauroidea as "the most inclusive clade containing Mosasaurus hoffmannii and Aigialosaurus dalmaticus, but not Dolichosaurus longicollis, Adriosaurus suessi, or Pontosaurus lesinensis".

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

Ectenosaurus is an extinct genus of marine lizard belonging to the mosasaur family. It is classified as part of the Plioplatecarpinae subfamily alongside genera like Angolasaurus and Platecarpus. Ectenosaurus is known from the Santonian and Campanian of Kansas, Alabama, and Texas.

<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.

<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.

<span class="mw-page-title-main">Mosasauria</span> Extinct squamates of the Cretaceous period

Mosasauria is a clade of aquatic and semiaquatic squamates that lived during the Cretaceous period. Fossils belonging to the group have been found in all continents around the world. Early mosasaurians like dolichosaurs were small long-bodied lizards that inhabited nearshore coastal and freshwater environments; the Late Cretaceous saw the rise of large marine forms, the mosasaurids, which are the clade's best-known members.

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 4 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.