Halszkaraptorinae

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Halszkaraptorines
Temporal range: Late Cretaceous,
75–71  Ma
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Possible Early Cretaceous record [1]
Halszkaraptor escuilliei holotype.png
Holotype specimen of Halszkaraptor escuilliei
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Saurischia
Clade: Theropoda
Family: Dromaeosauridae
Subfamily: Halszkaraptorinae
Cau et al., 2017
Type genus
Halszkaraptor escuilliei
Cau et al., 2017
Genera

Halszkaraptorinae is an extinct basal ("primitive") subfamily of Dromaeosauridae (or possibly Unenlagiidae) that includes the enigmatic genera Halszkaraptor , Natovenator , Mahakala , and Hulsanpes . Halszkaraptorines are definitively known only from Late Cretaceous strata in Asia, specifically in Mongolia. It is debated among researchers whether the group had a semiaquatic lifestyle.

Contents

History of discovery

Cretaceous-aged fossil localities of Mongolia; Halszkaraptorine fossils have been collected at the Khulsan (area A), Tugrik Shireh, and Ukhaa Tolgod localities (area B) Cretaceous-aged dinosaur fossil localities of Mongolia.PNG
Cretaceous-aged fossil localities of Mongolia; Halszkaraptorine fossils have been collected at the Khulsan (area A), Tugrik Shireh, and Ukhaa Tolgod localities (area B)

The first known remains of halszkaraptorines were found in sandstone sediments in 1970 during a Polish-Mongolian expedition at the Barun Goyot Formation, Gobi Desert. Later in 1982, they were described by Polish palaeontologist Halszka Osmólska and used as the holotype for the new genus and species Hulsanpes perlei , honoring the Mongolian paleontologist Altangerel Perle. Although the affinities of these fossils were not fully understood, they were tentatively interpreted as belonging to Deinonychosauria. [2] In 1992 dromaeosaurid-like fossils were recovered from the Tugriken Shire locality of the Djadokhta Formation and described as a new species in 2007 by Alan H Turner and team. This new taxon, Mahakala omnogovae , was regarded as a primitive dromaeosaurid mainly based on its body proportions. [3] In 2015 the Royal Belgian Institute of Natural Sciences received a small theropod fossil specimen, hailing from England and Japanese private collections. The specimen, through negotiations between the former institute, Eldonia and Mongolian authorities, was lastly returned to the Institute of Paleontology and Geology, Mongolian Academy of Sciences. According to associated documents of the specimen, it was illegally poached from the Djadokhta Formation (Ukhaa Tolgod locality; however, sediments may suggest that, alternatively, it was recovered from nearby Bayn Dzak locality) during an unknown year, eventually falling into private collections. The specimen was formally described in 2017 by Andrea Cau with colleagues, naming the genus and species Halszkaraptor escuilliei , in honor of Halszka Osmólska and François Escuillié, paleontologists who made negotiations for returning the poached specimen to Mongolia possible. With the naming of Halszkaraptor, the subfamily Halszkaraptorinae was also coined to contain this taxon and relatives, namely Hulsanpes and Mahakala. [4]

Description

Size of known halszkaraptorines compared to a human Halszkaraptorinae size comparison.png
Size of known halszkaraptorines compared to a human

Halszkaraptorines were relatively small theropods, reaching lengths similar to those of modern-day ducks. [3] [4] They are diagnosed by their long necks, proximal caudal vertebrae with oriented articular processes (projections of the vertebra fits with an adjacent vertebra) and prominent zygapophyseal laminae (plates of bone that form the posterior walls of each vertebra), a flattened ulna with a sharp posterior margin, ilium with a shelf-like supratrochanteric (above the trochanter of the femur) process, metacarpal III shaft transversely as thick as that of metacarpal II, a posterodistal surface on the femoral shaft with an elongate fossa bound by a lateral crest and the proximal half of metatarsal III being unconstricted and markedly convex anteriorly. [4]

Classification

Halszkaraptorinae is defined as the most inclusive clade that contains Halszkaraptor escuilliei but not Dromaeosaurus albertensis, Unenlagia comahuensis, Saurornithoides mongoliensis or Vultur gryphus . [4] The cladogram below is based on the phylogenetic analysis conducted in 2022 by Lee et al. in their description of Natovenator . [5]

Dromaeosauridae

Paleobiology

Life restoration of Natovenator Natovenator hunting fish.png
Life restoration of Natovenator

In 2017 a comparison of the fossils of Halszkaraptor with the bones of extant crocodilians and aquatic birds revealed evidence of a semiaquatic lifestyle. Cau and colleagues suggested that halszkaraptorines were obligate bipeds on land, but also swimmers that used its forelimbs to push through water and used their long necks for foraging. Such traits allowed them to exploit both terrestrial and aquatic paleoecosystems. [4] A 2024 study by Tse, Miller, and Pittman, focusing on the skull morphology and bite forces of various dromaeosaurids discovered that Halszkaraptor had a rapid bite unsuited to piscivorous feeding as previously hypothesized based on its skull morphology, and instead suggest it was an insectivore that hunted small invertebrates possibly in low-light conditions (at night or in murky water), since it likely had exceptional low-light vision among dromaeosaurids based on its relatively large orbit size. [6]

Other researchers have either disagreed with or merely followed Cau's interpretation as a semiaquatic dinosaur. In 2019, Brownstein argued that the features noted for Halszkaraptor do not directly support its ability to swim. He also suggested that this dinosaur may be a basal dromaeosaur with transitional features, [7] although Cau rebutted his claims a year later. [8] In 2021, Hone and Holtz noted that since Halszkaraptor and many modern aquatic birds with no flattened unguals is said to be semi-aquatic, having flattened unguals like Spinosaurus do not necessarily suggest that the animal can swim; they didn't propose their own view on this dinosaur's potential ability to swim. [9] In 2022, Fabbri and his colleagues argued against a semi-aquatic ecology for Halszkaraptor, noting that it had low bone density, a trait not observed in semi-aquatic animals. [10] In response, Cau has pointed out on his blog that swans similarly have low bone density yet have adaptations for semi-aquatic feeding. [11]

Related Research Articles

<i>Velociraptor</i> Dromaeosaurid dinosaur genus from the Late Cretaceous

Velociraptor is a genus of small dromaeosaurid dinosaurs that lived in Asia during the Late Cretaceous epoch, about 75 million to 71 million years ago. Two species are currently recognized, although others have been assigned in the past. The type species is V. mongoliensis, named and described in 1924. Fossils of this species have been discovered in the Djadochta Formation, Mongolia. A second species, V. osmolskae, was named in 2008 for skull material from the Bayan Mandahu Formation, China.

<span class="mw-page-title-main">Troodontidae</span> Extinct family of bird-like dinosaurs

Troodontidae is a clade of bird-like theropod dinosaurs from the Late Jurassic to Late Cretaceous. During most of the 20th century, troodontid fossils were few and incomplete and they have therefore been allied, at various times, with many dinosaurian lineages. More recent fossil discoveries of complete and articulated specimens, have helped to increase understanding about this group. Anatomical studies, particularly studies of the most primitive troodontids, like Sinovenator, demonstrate striking anatomical similarities with Archaeopteryx and primitive dromaeosaurids, and demonstrate that they are relatives comprising a clade called Paraves.

<span class="mw-page-title-main">Deinonychosauria</span> Extinct clade of dinosaurs

Deinonychosauria is a clade of paravian dinosaurs which lived from the Late Jurassic to the Late Cretaceous periods. Fossils have been found across the globe in North America, Europe, Africa, Asia, South America, and Antarctica, with fossilized teeth giving credence to the possibility that they inhabited Australia as well. This group of dinosaurs are known for their sickle-shaped toe claws and features in the shoulder bones.

<span class="mw-page-title-main">Dromaeosauridae</span> Family of theropod dinosaurs

Dromaeosauridae is a family of feathered coelurosaurian theropod dinosaurs. They were generally small to medium-sized feathered carnivores that flourished in the Cretaceous Period. The name Dromaeosauridae means 'running lizards', from Greek δρομαῖος (dromaîos), meaning 'running at full speed', 'swift', and σαῦρος (saûros), meaning 'lizard'. In informal usage, they are often called raptors, a term popularized by the film Jurassic Park; several genera include the term "raptor" directly in their name, and popular culture has come to emphasize their bird-like appearance and speculated bird-like behavior.

<i>Bagaceratops</i> Protoceratopsid dinosaur genus from the Late Cretaceous

Bagaceratops is a genus of small protoceratopsid dinosaurs that lived in Asia during the Late Cretaceous, around 72 to 71 million years ago. Bagaceratops remains have been reported from the Barun Goyot Formation and Bayan Mandahu Formation. One specimen may argue the possible presence of Bagaceratops in the Djadochta Formation.

<i>Borogovia</i> Extinct genus of dinosaurs

Borogovia is a troodontid theropod dinosaur genus which lived during the Late Cretaceous Period, in what is now Mongolia. It contains one species, Borogovia gracilicrus.

<i>Tylocephale</i> Extinct genus of dinosaurs

Tylocephale is a genus of pachycephalosaurid dinosaur, a group of dome-headed, herbivorous ornithischians, that lived during the Late Campanian stage of the Late Cretaceous in what is now Mongolia. It is known from a partial skull and associated mandible that were unearthed in 1971 by a Polish-Mongolian Expedition to the Barun Goyot Formation of the Gobi Desert. The specimen was described in 1974 by Polish paleontologists Teresa Maryańska and Halszka Osmólska as a new genus and species.

<i>Hulsanpes</i> Extinct genus of dinosaurs

Hulsanpes is a genus of halszkaraptorine theropod dinosaurs that lived during the Late Cretaceous in what is now the Barun Goyot Formation of Mongolia, about 75-72 million years ago. The remains were found in 1970 and formally described in 1982 by Halszka Osmólska, who noted that the genus is represented by an immature individual. Hulsanpes represents the first record of the basal dromaeosaurid subfamily Halszkaraptorinae.

<span class="mw-page-title-main">Archaeopterygidae</span> Family of dinosaurs

Archaeopterygidae is a group of paravian dinosaurs, known from the latest Jurassic and earliest Cretaceous of Europe. In most current classifications, it contains only the genera Archaeopteryx and Wellnhoferia. As its name suggests, Protarchaeopteryx was also once referred to this group, but most paleontologists now consider it an oviraptorosaur. Other referred genera, like Jurapteryx, Wellnhoferia, and "Proornis", are probably synonymous with Archaeopteryx or do not belong into this group. Jinfengopteryx was originally described as an archaeopterygid, though it was later shown to be a troodontid. A few studies have recovered Anchiornis and Xiaotingia to also be members of the Archaeopterygidae, though most subsequent analyses have failed to arrive at the same result. Uncertainties still exist, however, and it may not be possible to confidently state whether archaeopterygids are more closely related to modern birds or to deinonychosaurs barring new and better specimens of relevant species. Teeth attributable to archaeopterygids are known from the earliest Cretaceous (Berriasian) Cherves-de-Cognac locality and the Angeac-Charente bonebed of France.

<span class="mw-page-title-main">Barun Goyot Formation</span> Geological formation in Mongolia

The Barun Goyot Formation is a geological formation dating to the Late Cretaceous Period. It is located within and is widely represented in the Gobi Desert Basin, in the Ömnögovi Province of Mongolia.

<span class="mw-page-title-main">Avialae</span> Clade including all birds and their ancestors

Avialae is a clade containing the only living dinosaurs, the birds, and their closest relatives. It is usually defined as all theropod dinosaurs more closely related to birds (Aves) than to deinonychosaurs, though alternative definitions are occasionally used.

<span class="mw-page-title-main">Halszka Osmólska</span> Polish paleontologist

Halszka Osmólska was a Polish paleontologist who had specialized in Mongolian dinosaurs.

<span class="mw-page-title-main">Mahakala omnogovae</span> Extinct species of dinosaur

Mahakala is a genus of halszkaraptorine theropod dinosaur from the Campanian-age Upper Cretaceous Djadokhta Formation of Ömnögovi, Mongolia. It is based on a partial skeleton found in the Gobi Desert. Mahakala was a small dromaeosaurid, and its skeleton shows features that are also found in early troodontids and avialans. Despite its late appearance, it is among the most basal dromaeosaurids. Its small size, and the small size of other basal deinonychosaurians, suggests that small size appeared before flight capability in birds. The genus is named for Mahakala, one of eight protector deities (dharmapalas) in Tibetan Buddhism.

<i>Ceratonykus</i> Extinct genus of dinosaurs

Ceratonykus is a monospecific genus of alvarezsaurid dinosaur from Mongolia that lived during the Late Cretaceous in what is now the Barun Goyot Formation. The type and only species, Ceratonykus oculatus, is known from a fragmentary skeleton, including an incomplete skull, of an adult individual. It was named and described in 2009 by Vladimir Alifanov and Rinchen Barsbold. Its describers questioned the traditional placement of alvarezsaurs in Theropoda, instead suggesting they were ornithischians, but this has not been accepted since. Ceratonykus has an estimated length of 75 centimetres and weight of 760 grams. It has been considered as a possible junior synonym of Parvicursor.

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

This timeline of dromaeosaurid research is a chronological listing of events in the history of paleontology focused on the dromaeosaurids, a group of sickle-clawed, bird-like theropod dinosaurs including animals like Velociraptor. Since the Native Americans of Montana used the sediments of the Cloverly Formation to produce pigments, they may have encountered remains of the dromaeosaurid Deinonychus hundreds of years before these fossils came to the attention of formally trained scientists.

<span class="mw-page-title-main">Unenlagiidae</span> Extinct family of dinosaurs

Unenlagiidae is a proposed family of eumaniraptoran paravians that includes the subfamilies Unenlagiinae and possibly Halszkaraptorinae. Fossils of both subfamilies have been found in both Gondwanan and Laurasian deposits. The biology of the group suggests that some members were semiaquatic specialists.

<i>Halszkaraptor</i> Extinct genus of dinosaurs

Halszkaraptor is a genus of waterfowl-like dromaeosaurid dinosaurs from Mongolia that lived during the Late Cretaceous period. It contains only one known species, Halszkaraptor escuilliei.

<i>Natovenator</i> Genus of dromaeosaurid dinosaurs from the Late Cretaceous

Natovenator is a genus of halszkaraptorine dromaeosaurid dinosaur from the Late Cretaceous Barun Goyot Formation of Mongolia. The genus is known from a single species, N. polydontus. Natovenator is crucial to the understanding of halszkaraptorines due to it providing more support for the semi-aquatic lifestyle that has been proposed for this clade. This discovery is important as the semi-aquatic lifestyles of halszkaraptorines was contested in early 2022.

<i>Jaculinykus</i> Genus of alvarezsaurid dinosaurs

Jaculinykus is an extinct genus of alvarezsaurid theropod dinosaur from the Late Cretaceous Baruungoyot Formation of Mongolia. The genus contains a single species, J. yaruui, known from a nearly complete articulated skeleton including bones of the skull. Jaculinykus is notable for its unique hand, which has a hypertrophied first digit and greatly reduced second digit, which is intermediate between the tridactyl hand of Shuvuuia and monodactyl hand of Linhenykus.

<i>Harenadraco</i> Genus of troodontid dinosaurs

Harenadraco is an extinct genus of troodontid theropod dinosaurs from the Late Cretaceous Baruungoyot Formation of Mongolia. The genus contains a single species, H. prima, known from a fragmentary skeleton. Harenadraco represents the first troodontid known from the Baruungoyot Formation. Since members of this family are also known from the Nemegt and Djadochta Formations, the discovery of Harendraco indicates that troodontids were important faunal components of every formation within the Nemegt Basin.

References

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