Halisaurinae

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Halisaurinae
Temporal range: Late Cretaceous 86.3–66  Ma
Halisaurus arambourgi.JPG
Skeleton of Halisaurus arambourgi .
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Clade: Mosasauria
Family: Mosasauridae
Subfamily: Halisaurinae
Bardet et al., 2005
Genera

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. [1] 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 [2] 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, [3] indicating a more or less global distribution in the Late Cretaceous. Four genera are currently recognized: Eonatator , Halisaurus , Phosphorosaurus and Pluridens .

Contents

Description

Restoration of Halisaurus. Halisaurus arambourgi.jpg
Restoration of Halisaurus .

The Halisaurinae exhibit several characteristics that suggest they are more primitive than mosasaurs of more derived subfamilies. In particular, their flippers are poorly differentiated, meaning that while better adapted to life in oceans than plesiopedal mosasaur genera like Dallasaurus and Tethysaurus , they were poor swimmers compared to many of their contemporaries. Lacking swimming capabilities are quite surprising considering that most other small mosasaurs were adapted to be fast and nimble. The description of Phosphorosaurus ponpetelegans revealed that Phosphorosaurus was highly specialized to compensate for its lack of hydrophalangy. [4]

Despite their shortcomings, the Halisaurinae had diversified and reached a global distribution by the end of the Maastrichtian whilst other subfamilies, particularly the Plioplatecarpinae and Tylosaurinae, appear to have been in decline. [5] There is also evidence supporting that they were accomplished intercontinental migrators, with a known large-scale migration event involving Eonatator during the Campanian from the Western Interior Seaway of North America to what today is southern Sweden. [6]

Bardet et al. (2005, p. 464 [7] ) diagnosed the Halsaurinae as all mosasaurs more closely related to Halisaurus than Moanasaurus . Unambiguous character states were listed as follows: "premaxilla-maxilla sutural contact vertical anteriorly, oblique at midpoint and horizontal posteriorly; contact plane between the parietal and the supratemporal oblique; preaxial ridge extending on two-thirds of the length of the radius; tibia and fibula long and slender with slightly expanded extremities. Ambiguous characters include "dorsal median ridge borne on the anterior two-thirds of the frontal; frontal with ventral boss; parietal foramen surrounded by a ventral boss; quadrate with large infrastapedial process; coalescent infra- and suprastapedial processes of quadrate; zygosphene-zygantrum complex absent; synapophyses of the cervical vertebrae extending ventrally to the ventral surface of the centrum; fused haemal spines."

Phylogeny

Speculative restoration of Pluridens based on Halisaurus. Pluridens.png
Speculative restoration of Pluridens based on Halisaurus.

Designation of this subfamily followed many decades of confusion surrounding the type genus, Halisaurus, which had long been seen as (and remains) an important taxon in studies of mosasaur phylogeny. The confusion was especially centered on H. sternbergii, a species from the Mooreville Chalk Formation of Alabama and the Niobrara Chalk of Kansas. Originally, the species had been referred to the mosasaurine Clidastes , [8] then to Halisaurus (Russell, 1967; p. 369 [9] ), which was also considered a member of the Mosasaurinae at that time. Later workers [10] [11] questioned the phylogenetic position and monophyly of Halisaurus, in part because of striking morphological differences between H. sternbergii and the other known species of the taxon.

Several discoveries throughout the 1980s and 1990s helped shed light on Halisaurus , with more complete specimens of the type species H. platyspondylus being discovered and Phosphorosaurus ortliebi being momentarily reassigned to the genus by Lingham-Soliar (1996). [12] In 2005, the species Halisaurus sternbergii was reassigned to its own genus, Eonatator , along with the description of the new species Halisaurus arambourgi by Nathalie Bardet and colleagues. With the description of Eonatator as a closely related genus to Halisaurus, the two genera were grouped into the new subfamily Halisaurinae. Their study supported the model that the group was a sister-group to more advanced mosasaurs. [7] Daniel Madzia and Andrea Cau in 2017 defined Halisaurinae as "the most inclusive clade containing Halisaurus platyspondylus , but not Mosasaurus hoffmannii , Tylosaurus proriger , Tethysaurus nopcsai , or Yaguarasaurus colombianus ". [13] Since the description of Eonatator , two more species of Halisaurus , H. ortliebi and H. walkeri were recognised as separate genera; Phosphorosaurus and Pluridens respectively.

The recentmost major phylogenetic analysis of mosasaurs, conducted by Tiago R. Simões and colleagues in May 2017, recovered Halisaurus and the rest of the Halisaurinae as a sister group to the Mosasaurinae instead of the whole Mosasauridae. This would mean that the halisaurines are more closely related to the mosasaurines than the russellosaurines (genera such as Tylosaurus and Plesioplatecarpus ) are. [14]

The following cladogram is modified from Longrich et al. (2021) during the description of Pluridens serpentis , [15] with placement of higher taxa based on Madzia & Cau (2017). [13] In that study, Longrich et al. (2021) named the clades Halisaurini and Pluridensini to reflect the two major lineages of halisaurines, defining the former as "the most inclusive clade containing Halisaurus platyspondylus , but not Pluridens walkeri " and the latter as "the most inclusive clade containing Pluridens walkeri , but not Halisaurus platyspondylus ". [15]

In their 2023 description of the new Halisaurus species, H. hebae, Shaker et al. analyzed the phylogenetic relationships of members of the Halisaurinae. They suggested that Phosphorosaurus ponpetelegans and Eonatator coellensis were more closely related to the genus Halisaurus than the type species of their respective genera. They tentatively assigned these species to Halisaurus, with "Phosphorosaurus" ponpetelegans possibly representing a distinct genus in need of a new name. The results of their analyses are displayed in the cladogram below: [16]

Halisaurinae
Pluridensini

"Mooreville Chalk halisaurine" (AUMP 1486)

Pluridens serpentis

Pluridens walkeri

Pluridens calabaria

Halisaurini

Eonatator sternbergii

Phosphorosaurus ortliebi

Halisaurus ("Phosphorosaurus")ponpetelegans

Halisaurus("Eonatator")coellensis

Halisaurus hebae

Halisaurus arambourgi

Halisaurus platyspondylus

Species and taxonomy

Halisaurinae

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.

<i>Selmasaurus</i> Extinct genus of mosasaurids

Selmasaurus 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. Two species are known, S. russelli and S. johnsoni; both are exclusively known from Santonian deposits in the United States.

<span class="mw-page-title-main">Mosasaurinae</span> Subfamily of reptiles

The Mosasaurinae are a subfamily of mosasaurs, a diverse group of Late Cretaceous marine squamates. Members of the subfamily are informally and collectively known as "mosasaurines" and their fossils have been recovered from every continent except for South America.

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.

Eonatator is an extinct genus of marine lizard belonging to the mosasaur family. It is a close relative of Halisaurus, and part of the same subfamily, the Halisaurinae. It is known from the Late Cretaceous of North America, Colombia and Sweden. Originally, this taxon was included within Halisaurus, but was placed in its own genus, which also led to the subfamily Halisaurinae being created for the two genera.

<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. Globidens belongs to the family Mosasauridae, which consists of several genera of predatory marine lizards of various sizes that were prevalent during the Late Cretaceous. Specimens of Globidens have been discovered in Angola, Brazil, Morocco, Syria and the United States. Among mosasaurs, Globidens is probably most well known for the highly rounded, globe-like teeth that give it its name.

<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>Pluridens</i> Extinct genus of lizards

Pluridens is an extinct genus of marine lizard belonging to the Mosasauridae. Pluridens is placed in the subfamily Halisaurinae with the genera Phosphorosaurus, Eonatator and Halisaurus. Compared to related halisaurines, Pluridens had longer jaws with more teeth, and smaller eyes. It also grew large size, measuring 5–6 m (16–20 ft) long and perhaps over 9 m (30 ft) in some individuals. The jaws in some specimens are robust, and sometimes show injuries suggestive of combat. The jaws may have been used for fighting over mates or territories.

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

Liodon is a dubious genus of mosasaur from the Late Cretaceous, known from fragmentary fossils discovered in St James' Pit, England and possibly also the Ouled Abdoun Basin of Morocco. Though dubious and of uncertain phylogenetic affinities, Liodon was historically a highly important taxon in mosasaur systematics, being one of the genera on which the family Mosasauridae was based.

<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>Phosphorosaurus</i> Extinct genus of lizards

Phosphorosaurus is an extinct genus of marine lizard belonging to the mosasaur family. Phosphorosaurus is classified within the Halisaurinae subfamily alongside the genera Pluridens, Eonatator, and Halisaurus.

<span class="mw-page-title-main">Ouled Abdoun Basin</span> Phosphate basin in Morocco

The Oulad Abdoun Basin is a phosphate sedimentary basin located in Morocco, near the city of Khouribga. It is the largest in Morocco, comprising 44% of Morocco's phosphate reserves, and at least 26.8 billion tons of phosphate. It is also known as an important site for vertebrate fossils, with deposits ranging from the Late Cretaceous (Cenomanian-Turonian) to the Eocene epoch (Ypresian), a period of about 25 million years.

<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.

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

Gavialimimus is an extinct genus of plioplatecarpine mosasaur from the Maastrichtian of Morocco. The holotype MHNM.KHG.1231, an articulated skull and associated fragmentary postcrania, was found in the Ouled Abdoun Basin.

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

Xenodens is an extinct genus of marine lizard belonging to the mosasaur family. It currently contains a single species, X. calminechari, which is known from Late Maastrichtian phosphate deposits in the Ouled Abdoun Basin, Morocco. Its closest known relative is believed to be the durophagous Carinodens.

<i>Thalassotitan</i> Large bodied African mosasaur

Thalassotitan is an extinct genus of large mosasaurs that lived during the late Maastrichtian of the Cretaceous period in what is now Morocco, around 67 to 66 million years ago. The only known species is T. atrox, described in 2022 from fossils discovered in the Ouled Abdoun Basin, initially identified as coming from other genera such as Mosasaurus or Prognathodon. Hypothetical Thalassotitan specimens may have been found in other corners of the world, although researchers also note the possibility that they come from distinct, related taxa. It is considered to be close to the genera Prognathodon and Gnathomortis, together forming the tribe Prognathodontini. The prognathodontines are separated from other mosasaurs based on their massive jaws and robust teeth.

References

  1. Longrich, N. R., Bardet, N., Khaldoune, F., Yazami, O. K., & Jalil, N.-E. (2021). Pluridens serpentis, a new mosasaurid (Mosasauridae: Halisaurinae) from the Maastrichtian of Morocco and implications for mosasaur diversity. Cretaceous Research, 104882.
  2. Bardet, N., & Pereda-Suberbiola, X. (2001). The basal mosasaurid Halisaurus sternbergii from the Late Cretaceous of Kansas (North America): a review of the Uppsala type specimen. Comptes Rendus de l'Academie des Sciences-Series IIA-Earth and Planetary Science, 332(6), 395-402.
  3. "Fossilworks: Halisaurinae". fossilworks.org. Archived from the original on 12 December 2021. Retrieved 17 December 2021.
  4. Takuya Konishi, Michael W. Caldwell, Tomohiro Nishimura, Kazuhiko Sakurai & Kyo Tanoue (2015) A new halisaurine mosasaur (Squamata: Halisaurinae) from Japan: the first record in the western Pacific realm and the first documented insights into binocular vision in mosasaurs. Journal of Systematic Palaeontology (advance online publication) DOI:10.1080/14772019.2015.1113447 http://www.tandfonline.com/doi/full/10.1080/14772019.2015.1113447#abstract
  5. Polcyn, Michael J.; Jacobs, Louis L.; Araújo, Ricardo; Schulp, Anne S.; Mateus, Octávio (2014-04-15). "Physical drivers of mosasaur evolution". Palaeogeography, Palaeoclimatology, Palaeoecology. Physical drivers in the evolution of marine tetrapods. 400: 17–27. doi:10.1016/j.palaeo.2013.05.018.
  6. Lindgren, Johan; Siverson, Mikael (2005). "Halisaurus sternbergi, a Small Mosasaur with an Intercontinental Distribution". Journal of Paleontology. 79 (4): 763–773. doi:10.1666/0022-3360(2005)079[0763:HSASMW]2.0.CO;2. JSTOR   4095048. S2CID   130289272.
  7. 1 2 Bardet, N., Pereda Suberbiola, X., Iarochene, M., Bouya, B. & Amaghzaz, M. 2005. A new species of Halisaurus from the Late Cretaceous phosphates of Morocco, and the phylogenetical relationships of the Halisaurinae (Squamata: Mosasauridae). Zoological Journal of the Linnean Society, 143, 447–472.
  8. Wiman CJ. 1920. Some reptiles from the Niobrara group in Kansas. Bulletin of the Geological Institute of Uppsala18: 9-18 (9 figs., pls. II-IV).
  9. Russell DA. 1967. Systematics and morphology of American mosasaurs. Peabody Museum of Natural History, Yale University, Bulletin23.
  10. Wright KR. 1988. A new specimen of Halisaurus platyspondylus (Squamata: Mosasauridae) from the Navesink Formation (Maastrichtian) of New Jersey. Journal of Vertebrate Paleontology8 (Supplement 3): 29A-30A.
  11. Bell GL. Jr. 1997. A phylogenetic revision of North American and Adriatic Mosasauroidea. pp. 293-332 In: Callaway JM. and Nicholls EL, (eds.), Ancient Marine Reptiles, Academic Press: 501 pp.
  12. Lingham-Soliar, T. 1996. The first description of Halisaurus (Reptilia Mosasauridae) from Europe, from the Upper Cretaceous of Belgium. Bulletin de l'Institut royal des Sciences naturelles de Belgique, Sciences de la Terre, 66, 129–136.
  13. 1 2 Daniel Madzia; Andrea Cau (2017). "Inferring 'weak spots' in phylogenetic trees: application to mosasauroid nomenclature". PeerJ. 5: e3782. doi: 10.7717/peerj.3782 . PMC   5602675 . PMID   28929018.
  14. Simões, Tiago R.; Vernygora, Oksana; Paparella, Ilaria; Jimenez-Huidobro, Paulina; Caldwell, Michael W. (2017-05-03). "Mosasauroid phylogeny under multiple phylogenetic methods provides new insights on the evolution of aquatic adaptations in the group". PLOS ONE. 12 (5): e0176773. doi: 10.1371/journal.pone.0176773 . ISSN   1932-6203. PMC   5415187 . PMID   28467456.
  15. 1 2 Longrich, N. R., Bardet, N., Khaldoune, F., Yazami, O. K., & Jalil, N.-E. (2021). Pluridens serpentis, a new mosasaurid (Mosasauridae: Halisaurinae) from the Maastrichtian of Morocco and implications for mosasaur diversity. Cretaceous Research, 104882.
  16. Shaker, A. A.; Longrich, N. R.; Strougo, A.; Asan, A.; Bardet, N.; Mousa, M. K.; Tantawy, A. A.; Abu El-Kheir, G. A. (2023). "A new species of Halisaurus (Mosasauridae: Halisaurinae) from the lower Maastrichtian (Upper Cretaceous) of the Western Desert, Egypt". Cretaceous Research. 154. 105719. doi:10.1016/j.cretres.2023.105719.

Notes

    Further reading

    Bardet N, Suberbiola XP. 2001. The basal mosasaurid Halisaurus sternbergii from the Late Cretaceous of Kansas (North America): a review of the Uppsala type specimen. Comptes Rendus de l'Académie des Sciences, Série IIA332: 395-402.