Riparovenator

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Riparovenator
Temporal range: Barremian, 128  Ma
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Riparovenator holotype.webp
Holotype skull fragments
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Saurischia
Clade: Theropoda
Family: Spinosauridae
Clade: Ceratosuchopsini
Genus: Riparovenator
Barker et al., 2021
Type species
Riparovenator milnerae
Barker et al., 2021

Riparovenator ("riverbank hunter") is a genus of baryonychine spinosaurid dinosaur from the Early Cretaceous (Barremian) period of Britain. The genus contains a single species, Riparovenator milnerae.

Contents

Discovery and naming

Diagram by Dan Folkes showing known material of Riparovenator (front) and Ceratosuchops (rear) RiparovenatorCeratosuchops.webp
Diagram by Dan Folkes showing known material of Riparovenator (front) and Ceratosuchops (rear)

Between 2013 and 2017, spinosaurid fossils were uncovered at the beach near the Chilton Chine before being brought to Dinosaur Isle. Such remains had historically been referred to Baryonyx but were understood later to represent two new species. [1]

The holotype remains of this taxon consist of IWCMS 2014.95.6 (premaxillary bodies), IWCMS 2014.96.1, 2; 2020.448.1, 2 (a disarticulated braincase), and IWCMS 2014.96.3 (a partial lacrimal and prefrontal). Referred remains include a posterior nasal fragment (IWCMS 2014.95.7) and a caudal axial series of twenty-two vertebrae (IWCMS 2020.447.1-39), representing around fifty individual bones in total. All of the material was recovered from rocks in the Chilton Chine of the Wessex Formation. [1]

In 2021, the type species Riparovenator milnerae was named and described by a team of palaeontologists including Chris T. Barker, David W. E. Hone, Darren Naish, and others. The generic name is derived from the Latin rīpārius, "of the river bank", and vēnātor, "hunter". The specific name honors Angela Milner, deceased in August 2021. [1]

Life restoration Riparovenator milnerae by PaleoGeek v2.png
Life restoration

Classification

In their phylogenetic analysis, Barker et al. (2021) recovered Ceratosuchops within the Baryonychinae, as the sister taxon to the coeval Riparovenator . They are, in turn, in a clade containing Suchomimus , which they name Ceratosuchopsini. [1] [2]

Baryonychinae

ML1190 ( Iberospinus )

Baryonyx

Ceratosuchopsini

Suchomimus

Riparovenator

Ceratosuchops

In 2023, Sereno and colleagues tentatively combined Ceratosuchops and Riparovenator into a single taxonomic unit for their phylogenetic analysis. They reason that the different features between the two taxa could be attributed to individual variation, citing the cranial variation present in specimens of Allosaurus fragilis . Some of their supposed distinguishing features are also seen in parts of the braincase of Suchomimus, their closest relative. The results of their phylogenetic analysis (with Ceratosuchops and Riparovenator scored together) yielded similar results to those of Barker et al. (2021), with the Wessex baryonychine fossils recovered as the sister taxon to Suchomimus. [3]

Spinosauridae
Camarillasaurus
Life reconstruction of Camarillasaurus cirugedae.png
Baryonychinae
Baryonyx
Baryonyx walkeri by PaleoGeek v2.png
Ceratosuchopsini
Ceratosuchops (+Riparovenator)
Life reconstruction of Ceratosuchops inferodios.png
Suchomimus
Suchomimus tenerensis by PaleoGeek.png
Spinosaurinae
Ichthyovenator
Ichthyovenator laosensis by PaleoGeek.png
Vallibonavenatrix
Vallibonavenatrix cani by PaleoGeek.png
Spinosaurus
Spinosaurus aegyptiacus by PaleoGeek.png
Irritator
Irritator challengeri by PaleoGeek.png


Palaeoecology

Referred caudal material Riparovenatorcaudal.jpg
Referred caudal material

Riparovenator lived in a dry Mediterranean habitat in the Wessex Formation, where rivers were home to riparian galleries. [4] [5] Like most spinosaurids, it would have fed on aquatic prey as well as other terrestrial prey in these areas. [6] [7] [8]

Other dinosaurs from the Wessex Formation of the Isle of Wight the theropods Ceratosuchops, Neovenator , Eotyrannus , Aristosuchus , Thecocoelurus , Calamospondylus , and Ornithodesmus ; the ornithopods Iguanodon, Hypsilophodon , and Valdosaurus ; the sauropods Ornithopsis , Eucamerotus , and Chondrosteosaurus ; and the ankylosaur Polacanthus . [9] [1] Barker and colleagues stated in 2021 that the identification of the two additional spinosaurids from the Wealden Supergroup, Riparovenator and Ceratosuchops, has implications for potential ecological separation within Spinosauridae if these and Baryonyx were contemporary and interacted. They cautioned that it is possible the Upper Weald Clay and Wessex Formations and the spinosaurids known from them were separated in time and distance. [1]

It is generally thought that large predators occur with small taxonomic diversity in any area due to ecological demands, yet many Mesozoic assemblages include two or more sympatric theropods that were comparable in size and morphology, and this also appears to have been the case for spinosaurids. Barker and colleagues suggested that high diversity within Spinosauridae in a given area may have been the result of environmental circumstances benefiting their niche. While it has been generally assumed that only identifiable anatomical traits related to resource partitioning allowed for coexistence of large theropods, Barker and colleagues noted that this does not preclude that similar and closely related taxa could coexist and overlap in ecological requirements. Possible niche partitioning could be in time (seasonal or daily), in space (between habitats in the same ecosystems), or depending on conditions, and they could also have been separated by their choice of habitat within their regions (which may have ranged in climate). [1]

Related Research Articles

<i>Spinosaurus</i> Genus of spinosaurid dinosaur

Spinosaurus is a genus of spinosaurid dinosaur that lived in what now is North Africa during the Cenomanian to upper Turonian stages of the Late Cretaceous period, about 99 to 93.5 million years ago. The genus was known first from Egyptian remains discovered in 1912 and described by German palaeontologist Ernst Stromer in 1915. The original remains were destroyed in World War II, but additional material came to light in the early 21st century. It is unclear whether one or two species are represented in the fossils reported in the scientific literature. The best known species is S. aegyptiacus from Egypt, although a potential second species, S. maroccanus, has been recovered from Morocco. The contemporary spinosaurid genus Sigilmassasaurus has also been synonymized by some authors with S. aegyptiacus, though other researchers propose it to be a distinct taxon. Another possible junior synonym is Oxalaia from the Alcântara Formation in Brazil.

<i>Irritator</i> Spinosaurid theropod dinosaur genus from the Early Cretaceous Period

Irritator is a genus of spinosaurid dinosaur that lived in what is now Brazil during the Albian stage of the Early Cretaceous Period, about 113 to 110 million years ago. It is known from a nearly complete skull found in the Romualdo Formation of the Araripe Basin. Fossil dealers had acquired this skull and sold it to the State Museum of Natural History Stuttgart. In 1996, the specimen became the holotype of the type species Irritator challengeri. The genus name comes from the word "irritation", reflecting the feelings of paleontologists who found the skull had been heavily damaged and altered by the collectors. The species name is a homage to the fictional character Professor Challenger from Arthur Conan Doyle's novels.

<i>Baryonyx</i> Genus of theropod dinosaurs

Baryonyx is a genus of theropod dinosaur which lived in the Barremian stage of the Early Cretaceous period, about 130–125 million years ago. The first skeleton was discovered in 1983 in the Smokejack Clay Pit, of Surrey, England, in sediments of the Weald Clay Formation, and became the holotype specimen of Baryonyx walkeri, named by palaeontologists Alan J. Charig and Angela C. Milner in 1986. The generic name, Baryonyx, means "heavy claw" and alludes to the animal's very large claw on the first finger; the specific name, walkeri, refers to its discoverer, amateur fossil collector William J. Walker. The holotype specimen is one of the most complete theropod skeletons from the UK, and its discovery attracted media attention. Specimens later discovered in other parts of the United Kingdom and Iberia have also been assigned to the genus, though many have since been moved to new genera.

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

Suchomimus is a genus of spinosaurid dinosaur that lived between 125 and 112 million years ago in what is now Niger, West Africa, during the Aptian to early Albian stages of the Early Cretaceous period. It was named and described by paleontologist Paul Sereno and colleagues in 1998, based on a partial skeleton from the Elrhaz Formation. Suchomimus's long and shallow skull, similar to that of a crocodile, earns it its generic name, while the specific name Suchomimus tenerensis alludes to the locality of its first remains, the Ténéré Desert.

The Isle of Wight is one of the richest dinosaur localities in Europe, with over 20 species of dinosaur having been recognised from the early Cretaceous Period, some of which were first identified on the island, as well as the contemporary non-dinosaurian species of crocodile, turtle and pterosaur.

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

Neovenator is a genus of carcharodontosaurian theropod dinosaur. It is known from several skeletons found in the Early Cretaceous (Hauterivian-Barremian) Wessex Formation on the south coast of the Isle of Wight, southern England. It is one of the best known theropod dinosaurs from the Early Cretaceous of Europe.

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

The Spinosauridae are a clade or family of tetanuran theropod dinosaurs comprising ten to seventeen known genera. Spinosaurid fossils have been recovered worldwide, including Africa, Europe, South America and Asia. Their remains have generally been attributed to the Early to Mid Cretaceous.

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

Eotyrannus is a genus of tyrannosauroid theropod dinosaur hailing from the Early Cretaceous Wessex Formation beds, included in Wealden Group, located in the southwest coast of the Isle of Wight, United Kingdom. The remains (MIWG1997.550), consisting of assorted skull, axial skeleton and appendicular skeleton elements, from a juvenile or subadult, found in a plant debris clay bed, were described by Hutt et al. in early 2001. The etymology of the generic name refers to the animal's classification as an early tyrannosaur or "tyrant lizard", while the specific name honors the discoverer of the fossil.

<span class="mw-page-title-main">Darren Naish</span> British palaeontologist and science writer (born 1975)

Darren William Naish is a British vertebrate palaeontologist, author and science communicator.

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

Yaverlandia is a genus of maniraptoran dinosaur. Known from a partial fossil skull found in Lower Cretaceous strata of the Wessex Formation on the Isle of Wight. it was described as the earliest known member of the pachycephalosaurid family, but research by Darren Naish shows it to have actually been a theropod, seemingly a maniraptoran. The type species is Y. bitholus.

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

Aristosuchus is a genus of small coelurosaurian dinosaur whose name was derived from the Greek ἄριστος and σουχος. It shared many characteristics with birds.

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

Cristatusaurus is a genus of theropod dinosaur that lived during the Early Cretaceous Period of what is now Niger, 112 million years ago. It was a baryonychine member of the Spinosauridae, a group of large bipedal carnivores with well-built forelimbs and elongated, crocodile-like skulls. The type species Cristatusaurus lapparenti was named in 1998 by scientists Philippe Taquet and Dale Russell, on the basis of jaw bones and some vertebrae. Two claw fossils were also later assigned to Cristatusaurus. The animal's generic name, which means "crested reptile", alludes to a sagittal crest on top of its snout; while the specific name is in honor of the French paleontologist Albert-Félix de Lapparent. Cristatusaurus is known from the Albian to Aptian Elrhaz Formation, where it would have coexisted with sauropod and iguanodontian dinosaurs, other theropods, and various crocodylomorphs.

<span class="mw-page-title-main">Wessex Formation</span> Early Cretaceous geological formation in England

The Wessex Formation is a fossil-rich English geological formation that dates from the Berriasian to Barremian stages of the Early Cretaceous. It forms part of the Wealden Group and underlies the younger Vectis Formation and overlies the Durlston Formation. The dominant lithology of this unit is mudstone with some interbedded sandstones. It is part of the strata of the Wessex Basin, exposed in both the Isle of Purbeck and the Isle of Wight. While the Purbeck sections are largely barren of vertebrate remains, the Isle of Wight sections are well known for producing the richest and most diverse fauna in Early Cretaceous Europe.

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

Oxalaia is a genus of spinosaurid dinosaur that lived in what is now the Northeast Region of Brazil during the Cenomanian stage of the Late Cretaceous period, sometime between 100.5 and 93.9 million years ago. Its only known fossils were found in 1999 on Cajual Island in the rocks of the Alcântara Formation, which is known for its abundance of fragmentary, isolated fossil specimens. The remains of Oxalaia were described in 2011 by Brazilian palaeontologist Alexander Kellner and colleagues, who assigned the specimens to a new genus containing one species, Oxalaia quilombensis. The species name refers to the Brazilian quilombo settlements. Oxalaia quilombensis is the eighth officially named theropod species from Brazil and the largest carnivorous dinosaur discovered there. It is closely related to the African genus Spinosaurus, and/or may be a junior synonym of this taxon.

<i>Ichthyovenator</i> Genus of dinosaur

Ichthyovenator is a genus of spinosaurid dinosaur that lived in what is now Laos, sometime between 125 and 113 million years ago, during the Aptian stage of the Early Cretaceous period. It is known from fossils collected from the Grès supérieurs Formation of the Savannakhet Basin, the first of which were found in 2010, consisting of a partial skeleton without the skull or limbs. This specimen became the holotype of the new genus and species Ichthyovenator laosensis, and was described by palaeontologist Ronan Allain and colleagues in 2012. The generic name, meaning "fish hunter", refers to its assumed piscivorous lifestyle, while the specific name alludes to the country of Laos. In 2014, it was announced that more remains from the dig site had been recovered; these fossils included teeth, more vertebrae (backbones) and a pubic bone from the same individual.

<i>Ostafrikasaurus</i> Genus of theropod dinosaur

Ostafrikasaurus is a genus of theropod dinosaur from the Late Jurassic period of what is now Lindi Region, Tanzania. It is known only from fossil teeth discovered sometime between 1909 and 1912, during an expedition to the Tendaguru Formation by the Natural History Museum of Berlin. Eight teeth were originally attributed to the dubious dinosaur genus Labrosaurus, and later to Ceratosaurus, both known from the North American Morrison Formation. Subsequent studies attributed two of these teeth to a spinosaurid dinosaur, and in 2012, Ostafrikasaurus crassiserratus was named by French palaeontologist Eric Buffetaut, with one tooth as the holotype, and the other referred to the same species. The generic name comes from the German word for German East Africa, the former name of the colony in which the fossils were found, while the specific name comes from the Latin words for "thick" and "serrated", in reference to the form of the animal's teeth.

<i>Vallibonavenatrix</i> Genus of spinosaurid theropod dinosaur

Vallibonavenatrix is a genus of spinosaurid dinosaur from the Early Cretaceous (Barremian) Arcillas de Morella Formation of Castellón, Spain. The type and only species is Vallibonavenatrix cani, known from a partial skeleton.

<i>Ceratosuchops</i> Genus of baryonychine spinosaur from the Early Cretaceous

Ceratosuchops is a genus of spinosaurid from the Early Cretaceous (Barremian) of Britain.

<span class="mw-page-title-main">Baryonychinae</span> Subfamily of dinosaurs (fossil)

Baryonychinae is an extinct clade or subfamily of spinosaurids from the Early Cretaceous (Valanginian-Albian) of Britain, Portugal, and Niger. The clade was named by Charig & Milner in 1986 and defined by Sereno et al. in 1998 and Holtz et al. in 2004 as all taxa more closely related to Baryonyx walkeri than to Spinosaurus aegyptiacus.

<i>Iberospinus</i> Extinct genus of spinosaurid dinosaur

IberospinusIPA:[aɪbiːʌroʊs̠piːnʊs̠] or IPA:[aɪbiːʌroʊs̠paɪnʌs̠] is an extinct genus of spinosaurid dinosaur from the Early Cretaceous (Barremian) Papo Seco Formation of Portugal. The genus contains a single species, I. natarioi, known from several assorted bones belonging to one individual. Iberospinus represents one of five known spinosaurid taxa from the Iberian Peninsula, the others being Camarillasaurus, Protathlitis, Riojavenatrix, and Vallibonavenatrix. It is important for its implications of the geographical origin of Spinosauridae and the suggested presence of an at least semi-aquatic lifestyle early in the evolution of this clade.

References

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  2. Naish, Darren (29 September 2021). "Two New Spinosaurid Dinosaurs from the English Cretaceous". Tetrapod Zoology.
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  7. "'Hell heron' dinosaur is new species found on Isle of Wight".
  8. "'Horned crocodile-faced hell heron' is one of two new Isle of Wight dinosaur discoveries". 29 September 2021.
  9. Martill, D. M.; Hutt, S. (1996). "Possible baryonychid dinosaur teeth from the Wessex Formation (Lower Cretaceous, Barremian) of the Isle of Wight, England". Proceedings of the Geologists' Association. 107 (2): 81–84. Bibcode:1996PrGA..107...81M. doi:10.1016/S0016-7878(96)80001-0.