Oxalaia

Last updated

Contents

Oxalaia
Temporal range: Late Cretaceous, (Cenomanian)
100.5–93.9  Ma
Holotype of Oxalaia quilombensis.PNG
Holotype snout in multiple views
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Saurischia
Clade: Theropoda
Family:† Spinosauridae
Genus:† Oxalaia
Kellner et al., 2011
Species:
†O. quilombensis
Binomial name
†Oxalaia quilombensis
Kellner et al., 2011
Synonyms

Oxalaia (in reference to the African deity Oxalá ) 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.

Although Oxalaia is known only from two partial skull bones, Kellner and colleagues found that its teeth and cranium had a few distinct features not seen in other spinosaurids or theropods, including two replacement teeth in each socket and a very sculptured secondary palate. Oxalaia's habitat was tropical, heavily forested, and surrounded by an arid landscape. This environment had a large variety of lifeforms also present in Middle-Cretaceous North Africa, due to the connection of South America and Africa as parts of the supercontinent Gondwana. As a spinosaurid, the traits of Oxalaia's skull and dentition indicate a partly piscivorous (fish-eating) lifestyle similar to that of modern crocodilians. Fossil evidence suggests spinosaurids also preyed on other animals such as small dinosaurs and pterosaurs.

Discovery and naming

Map showing the Northeast Region of Brazil, with the discovery sites of three spinosaurine fossil specimens in the Araripe and Sao Luis-Grajau Basins marked. From top to bottom: Oxalaia, Irritator, and Angaturama. Spinosaur Taxonomy Map.png
Map showing the Northeast Region of Brazil, with the discovery sites of three spinosaurine fossil specimens in the Araripe and São Luís-Grajaú Basins marked. From top to bottom: Oxalaia, Irritator , and Angaturama.

Oxalaia stems from the Alcântara Formation, a succession of sedimentary rocks that is part of the Itapecuru Group of the São Luís-Grajaú Basin, in northeastern Brazil. These rocks have been dated by scientists to the Cenomanian stage of the Late Cretaceous period, 100.5 to 93.9 million years ago. [1] [2] Outcropping at the northern coast of the formation, the Laje do Coringa locality is made up mostly of sandstones and mudstones, along with conglomerate rock layers containing fossil plant and vertebrate fragments. [3] These sediments were deposited under marine and fluvial conditions similar to those of the Bahariya Formation in Egypt, where Spinosaurus remains have been found. [1] [4] In 1999, fossils of Oxalaia were recovered from the Laje do Coringa. [5] Palaeontologist Elaine Machado, of the National Museum of Rio de Janeiro, was surprised to find such a well-preserved fossil at the site and stated in a press release that "this is how most scientific discoveries happen, it was by accident". [6] The finding was a rare occurrence due to the erosive nature of the tides at the deposit, which are responsible for the fragmented state of most fossils in the bone bed; remains not found on site are often removed from the formation by wave action. [5] Generally, the majority of fossil remains found at the Alcântara Formation consist of teeth and isolated skeletal elements, of which the Laje do Coringa site has yielded hundreds. [1] [5] [7]

Diagram illustrating known jaw material in place Oxalaia quilombensis.PNG
Diagram illustrating known jaw material in place

Oxalaia is one of three spinosaurid dinosaurs discovered in Brazil, the other two being Irritator and its possible synonym Angaturama, both of which were also initially known from partial skulls. They were discovered in the Romualdo Formation of the Santana Group, part of the Araripe Basin. Microfossils date this formation to the Albian, around nine to six million years before Oxalaia. [5] [8] [9] The fossil record of spinosaurids is poor compared to those of other theropod groups; very few body fossils are known and most genera have been erected from isolated elements such as vertebra or teeth. [10] [11] The holotype specimen of Oxalaia quilombensis, designated MN 6117-V, was found in situ (at its original place of deposition) with part of the left side embedded in the rock matrix; it consists of the fused premaxillae (frontmost snout bones) from a large individual. An isolated and incomplete left maxilla (main upper jaw bone) fragment (MN 6119-V) was referred to Oxalaia because it showed the same general traits occurring in spinosaurids, the maxilla was discovered on the rock surface, having possibly moved from its original location after erosion. Both bone fragments were found on Cajual Island, Maranhão, in the Northeast Region of Brazil, and were housed at the National Museum of Rio de Janeiro. [5] In 2018, a fire engulfed the palace housing the museum, [12] possibly destroying Oxalaia's specimens, along with various other fossils found in Brazil. [13] Besides the partial skull bones, numerous spinosaurid teeth had earlier been reported from the Laje do Coringa site. [5] Two partial caudal (tail) vertebrae from the formation have been referred to the spinosaurid species Sigilmassasaurusbrevicollis . [1] American palaeontologist Mickey Mortimer informally noted that these may instead belong to Oxalaia. [14]

The discoveries of Oxalaia and of the Late Cretaceous reptiles Pepesuchus and Brasiliguana were announced in a presentation by the Brazilian Academy of Sciences in March 2011. [15] [16] Machado described Oxalaia as "the dominant reptile of [what is now] Cajual Island". She stated that there is interest in spinosaurids in Brazil and abroad because of their debut in the Jurassic Park franchise and their distinctiveness among other carnivorous dinosaurs. [15] The species description of Oxalaia was written by Brazilian palaeontologists Alexander Kellner, Elaine Machado, Sergio Azevedo, Deise Henriques, and Luciana Carvalho. This paper, among many others, were composed into a volume of 20 works on prehistoric biodiversity that was published by the academy in March 2011. [6] The type species Oxalaia quilombensis is the eighth officially named species of theropod from Brazil. The generic name Oxalaia is derived from the name of the African deity Oxalá, which was introduced into Brazil during the slavery period. The specific name quilombensis refers to the quilombo settlements like those on Cajual Island, which were founded by escaped slaves. [5]

Specimen UFMA 1.10.240, a distal caudal vertebra which was discovered in the Alcantara Formation of Brazil was assigned to Sigilmassasaurus in 2002. [17]

Description

Tentative size estimate, with the animal in a swimming position Oxalaia Size Chart.svg
Tentative size estimate, with the animal in a swimming position

The holotype premaxillae are together approximately 201 millimetres (7.9 inches) long, with a preserved width of 115 mm (4.5 in) (maximal estimated original width is 126 mm (5.0 in)), and a height of 103 mm (4.1 in). Based on skeletal material from related spinosaurids, the skull of Oxalaia would have been an estimated 1.35 metres (4.4 feet) long; [5] this is smaller than Spinosaurus's skull, which was approximated at 1.75 m (5 ft 9 in) long by Italian palaeontologist Cristiano Dal Sasso and colleagues in 2005. [18] Kellner and his team compared the Dal Sasso specimen (MSNM V4047) to Oxalaia's original snout in 2011; from this they estimated Oxalaia at 12 to 14 m (39 to 46 ft) in length and 5 to 7 tonnes (5.5 to 7.7 short tons ; 4.9 to 6.9 long tons ) in weight, making it the largest known theropod from Brazil, [5] the second largest being Pycnonemosaurus, which was estimated at 8.9 m (29 ft) by one study. [15] [19]

The tip of the rostrum (snout) is enlarged and the rear-end constricted, forming the terminal rosette shape that distinguishes spinosaurids; [5] this form would have interlocked with the also-expanded front of the dentary (tooth-bearing bone of the mandible ). [20] The rostrum of Oxalaia features broad, deep foramina (holes) that are possibly nutrient canals for blood vessels and nerves; it is also rounder in side view than that of Spinosaurus, whose upper jaw ends in a more acute downward angle as shown by specimens MSNM V4047 and MNHN SAM 124. The maxillae show a pair of elongated and thin processes extending forwards along the midline of the roof of the mouth; they are encased between the premaxillae and border an elaborate, triangle-shaped pit at their front end. Similar processes are present in Suchomimus , Cristatusaurus , and MNHN SAM 124, although not as exposed. [5] These structures compose the animal's secondary palate. [5] [21] The undersides of the premaxillae are greatly ornamented in Oxalaia, in contrast to the smoother condition it has in other spinosaurids. [5]

Hypothetical life restoration based on relatives Oxalaia quilombensis by PaleoGeek.png
Hypothetical life restoration based on relatives

The premaxillae have seven alveoli (tooth sockets) on each side, the same number found in Angaturama, Cristatusaurus, Suchomimus, and MNHN SAM 124 (referred to Spinosaurus); MSNM V4047, another upper jaw specimen from Spinosaurus, had only six. It cannot be confirmed whether this lower number of teeth is due to ontogeny; for that, a larger sample size is necessary. A large diastema (gap in tooth row) separates the third tooth socket from the fourth; this is observed in all other spinosaurids, being smaller in Suchomimus. Another diastema of nearly equal length is found between the fifth and sixth alveolus; this diastema is seen in MNHN SAM 124 and is much longer in MSNM V4047 but is absent from Suchomimus and Cristatusaurus. The maxilla fragment referred to Oxalaia (MN 6119-V) has two alveoli and a broken third one that includes a partial tooth. Like the premaxilla, it had preserved nutrient canals. It also features a shallow dent in the middle, suggesting it was located near the external nares (bony nostrils). Small fragments inside some of the remaining alveoli show that unlike its Early Cretaceous relatives Suchomimus and Cristatusaurus, Oxalaia lacked serrations on its teeth. Apart from the single, functional tooth in each socket, there were two replacement teeth, [5] which according to Kellner are "a common feature in sharks or in some reptiles, but not in theropods". [16] A cross-section of the teeth showed the typical oval shape exhibited by spinosaurs rather than the lateral compression of other theropod teeth. [5]

The spinosaurid teeth reported from Laje do Coringa were classified into two primary morphotypes by Brazilian palaeontologist Manuel Medeiros in 2006. Both show typical spinosaurine dentition, though morphotype II has smoother tooth enamel than the first. [22] Oxalaia's teeth display a closer morphology to morphotype I while the second grouping of teeth represent either worn down morphotype I teeth or an undescribed spinosaurine from the Alcântara Formation. [5]

Classification

Size of various spinosaurids (Oxalaia in green, third from left) compared with a human Spinosauridae Size Diagram by PaleoGeek - Version 2.svg
Size of various spinosaurids (Oxalaia in green, third from left) compared with a human

The type elements of Oxalaia closely resemble those of specimens MSNM V4047 and MNHN SAM 124, both referred to Spinosaurus aegyptiacus. Kellner and colleagues differentiated Oxalaia from it and other spinosaurids by its autapomorphic (distinguishing) craniodental features, like its sculptured palatal part of the premaxillae, and the possession of two replacement teeth in each position. [5] [21] More fragmentary spinosaurids such as Siamosaurus and "Sinopliosaurus" fusuiensis are based only on teeth, making them difficult to separate from other taxa. The habit of naming theropods from isolated teeth or tooth fragments has resulted in many invalid and synonymous genera; it has also occurred with spinosaurids and is compounded by the common lack of overlapping skeletal remains—a precondition of validly distinguishing taxa. [21] [23]

Labeled skull diagram of the related Spinosaurus Spinosaurus skull en.svg
Labeled skull diagram of the related Spinosaurus

In 2017, a phylogenetic analysis by the Brazilian palaeontologists Marcos Sales and Cesar Schultz concluded that Oxalaia was more closely related to African spinosaurines than to Brazilian spinosaurines like Angaturama, as indicated by a wider snout and the lack of a dorsal sagittal crest on the premaxillae. The Brazilian genera Oxalaia and Angaturama were recovered as the two closest relatives of Spinosaurus, Oxalaia forming its sister taxon. Though fragmentary, the Brazilian material indicates that spinosaurines were more diverse than previously recognized. Spinosaurus differs from Oxalaia by its significantly more widely spaced tooth sockets, the presence of a slight narrowing between its third and fourth sockets, and the sharper slope of its snout. Oxalaia is currently assigned to the subfamily Spinosaurinae due to the morphology of its upper jaw and the absence of fine serrations on its teeth that typify baryonychines. [5] [21] Below is a cladogram by Sales and Schultz, in which Oxalaia is grouped in the Spinosaurinae, as a closer relative to Spinosaurus than Angaturama. [21]

Spinosauridae

In 2020, a paper by Robert Smyth and colleagues assessing spinosaurines from the Kem Kem Group did not find the autapomorphies of Oxalaia quilombensis sufficient enough to warrant a separate taxon, but instead considered them a result of individual variation. The authors thus considered the species a junior synonym of Spinosaurus aegyptiacus. If supported by future studies, this would imply Spinosaurus aegyptiacus had a wider distribution and support a faunal exchange scenario between South America and Africa during the Cenomanian when there was little separation of South America and Africa by water, which allowed Spinosaurus aegyptiacus to traverse the short distance of the sea into South America. [24]

Palaeoecology

Generalised locations of spinosaurid fossil discoveries from the Albian-Cenomanian, 113 to 93.9 million years ago, marked on a map of that time span. Spinosaurid fossils palaeogeographic map.png
Generalised locations of spinosaurid fossil discoveries from the Albian-Cenomanian, 113 to 93.9 million years ago, marked on a map of that time span.

The Late Cretaceous deposits of the Alcântara Formation have been interpreted as a humid habitat of tropical forests dominated by conifers, ferns, and horsetails. These forests were surrounded by an arid-to-semi-arid landscape that was probably subjected to brief periods of heavy rainfall followed by lengthy dry periods. [1] [25] A great abundance and variety of animal taxa, such as dinosaurs, pterosaurs, snakes, molluscs, crocodilians, notosuchids, and fish have been discovered in the formation. Aquatic taxa known from the deposits include the large coelacanth Mawsonia gigas ; the ray Myliobatis sp. (of uncertain species); two sclerorhynchid sawfishes; as well as several bony fish, ray-finned fish, and lungfish species. [1] [26] Dinosaur fossil remains suggest the presence of diplodocoids like Itapeuasaurus cajapioensis , basal titanosaurs, a giant Carcharodontosaurid sp., a noasaurid closely related to Masiakasaurus , and a dromaeosaurid. Also, characteristic teeth and a vertebral centra were referred to Spinosaurus sp. [1] [27]

Most of the flora and fauna discovered in the Alcântara Formation was also present in North Africa in the Kem Kem Beds of Morocco during the Cenomanian; with a few exceptions including Oxalaia quilombensis, Atlanticopristis equatorialis, Equinoxiodus alcantariensis , and Coringasuchus anisodontis . According to Medeiros and colleagues, the Laje do Coringa assemblage may also be linked to the contemporaneous Bahariya Formation in Egypt, which holds a distinct combination of key taxa constituting Spinosaurus aegyptiacus, Carcharodontosaurus saharicus, and Onchopristis numidus. This extreme similarity between the Cretaceous biota of Brazil with that of Africa is a result of their connection as parts of the supercontinent Gondwana (which comprised most landmasses of the modern southern hemisphere). This connection was broken by rifting and sea-floor spreading 130–110 million years ago. Afterwards, the transoceanic assemblages would have continued to evolve separately, contributing to small differences between taxa. [1] [28] Machado stated that Cajual Island was still attached to the African continent during the Cenomanian. [6] Similarly, Medeiros and colleagues noted that the presence of an island chain or other lasting land connection during that time could explain the faunal similarities. [1]

An Indian gharial, displaying the same interlocking rosette shape seen in spinosaurid snout tips Gavialis gangeticus, ZOO Praha 045 (Flipped and Cropped).jpg
An Indian gharial, displaying the same interlocking rosette shape seen in spinosaurid snout tips

As a spinosaur, Oxalaia would have had large, robust forelimbs; relatively short hindlimbs; elongated neural spines (upwards projections of the vertebrae) forming a ridge or sail on its back; and tall neural spines on its caudal vertebrae which—similar to the tails of modern crocodilians—may have aided in swimming. [10] [29] Spinosaurids likely spent most of their time near or in water and fed mostly on aquatic animals, avoiding direct competition with other large predators but being able to sustain themselves on terrestrial animals if necessary. Such behavior is observed in cases such as juvenile Iguanodontid bones found in the stomach cavity of a Baryonyx fossil and an Irritator tooth embedded in pterosaur remains. [10] [30] The conical, transversely oval-shaped teeth of Oxalaia and its nasal openings, that were retracted further back on the skull than in most theropods (likely to avoid water entering its nostrils while fishing) are characteristic of spinosaurids. Both features are useful adaptations for catching and feeding on fish. [5] [10] [20] The expanded, interlocking front jaws and piercing teeth of spinosaurs worked as an efficient fish trap, a trait also exhibited by the Indian gharial—the most piscivorous extant crocodilian. [20] Kellner compared the general appearance of spinosaurid skulls to those of alligators. [16]

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 100 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>Carcharodontosaurus</i> Genus of carcharodontosaurid dinosaur from the Cretaceous period

Carcharodontosaurus is a genus of carnivorous theropod dinosaur that lived in North Africa from about 100 to 94 million years ago during the Cenomanian stage of the Late Cretaceous. Two teeth of the genus, now lost, were first described from Algeria by French paleontologists Charles Depéret and Justin Savornin as Megalosaurus saharicus. A partial skeleton was collected by crews of German paleontologist Ernst Stromer during a 1914 expedition to Egypt. Stromer did not report the Egyptian find until 1931, in which he dubbed the novel genus Carcharodontosaurus, making the type species C. saharicus. Unfortunately, this skeleton was destroyed during the Second World War. In 1995 a nearly complete skull of C. saharicus, the first well-preserved specimen to be found in almost a century, was discovered in the Kem Kem Beds of Morocco; it was designated the neotype in 1996. Fossils unearthed from the Echkar Formation of northern Niger were described and named as another species, C. iguidensis, in 2007.

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

Suchomimus is a genus of spinosaur dinosaur that lived between 125 and 112 million years ago in what is now Niger, north 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 Dese.

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

Spinosauridae is 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>Siamosaurus</i> Potentially dubious genus of spinosaurid theropod dinosaur

Siamosaurus is a genus of spinosaurid dinosaur that lived in what is now known as China and Thailand during the Early Cretaceous period and is the first reported spinosaurid from Asia. It is confidently known only from tooth fossils; the first were found in the Sao Khua Formation, with more teeth later recovered from the younger Khok Kruat Formation. The only species Siamosaurus suteethorni, whose name honours Thai palaeontologist Varavudh Suteethorn, was formally described in 1986. In 2009, four teeth from China previously attributed to a pliosaur—under the species "Sinopliosaurus" fusuiensis—were identified as those of a spinosaurid, possibly Siamosaurus. It is yet to be determined if two partial spinosaurid skeletons from Thailand and an isolated tooth from Japan also belong to Siamosaurus.

<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.

<i>Sigilmassasaurus</i> Spinosaurid theropod dinosaur genus from Cretaceous Period

Sigilmassasaurus is a controversial genus of spinosaurid dinosaur that lived approximately 100 to 94 million years ago during the Late Cretaceous Period in what is now northern Africa. Named in 1996 by Canadian paleontologist Dale Russell, it contains a single species, Sigilmassasaurus brevicollis. The identity of the genus has been debated by scientists, with some considering its fossils to represent material from the closely related species Spinosaurus aegyptiacus, while others have classified it as a separate taxon, forming the clade Spinosaurini with Spinosaurus as its sister taxon.

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

Suchosaurus is a spinosaurid dinosaur from Cretaceous England and Portugal, originally believed to be a genus of crocodile. The type material, consisting of teeth, was used by British palaeontologist Richard Owen to name the species S. cultridens in 1841. Later in 1897, French palaeontologist Henri-Émile Sauvage named a second species, S. girardi, based on two fragments from the mandible and one tooth discovered in Portugal. Suchosaurus is possibly a senior synonym of the contemporary spinosaurid Baryonyx, but is usually considered a dubious name due to the paucity of its remains, and is considered an indeterminate baryonychine. In the Wadhurst Clay Formation of what is now southern England, Suchosaurus lived alongside other dinosaurs, as well as plesiosaurs, mammals, and crocodyliforms.

<i>Xixiasaurus</i> Genus of dinosaur

Xixiasaurus is a genus of troodontid dinosaur that lived during the Late Cretaceous Period in what is now China. The only known specimen was discovered in Xixia County, Henan Province, in central China, and became the holotype of the new genus and species Xixiasaurus henanensis in 2010. The names refer to the areas of discovery, and can be translated as "Henan Xixia lizard". The specimen consists of an almost complete skull, part of the lower jaw, and teeth, as well as a partial right forelimb.

The Alcântara Formation is a geological formation in northeastern Brazil whose strata date back to the Cenomanian of the Late Cretaceous.

<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>Camarillasaurus</i> Extinct genus of dinosaurs

Camarillasaurus is a genus of theropod dinosaur from the Early Cretaceous period (Barremian) of Camarillas, Teruel Province, in what is now northeastern Spain. Described in 2014, it was originally identified as a ceratosaurian theropod, but later studies suggested affinities to the Spinosauridae. If it does represent a spinosaur, Camarillasaurus would be one of five spinosaurid taxa known from the Iberian peninsula, the others being Iberospinus, Protathlitis, Riojavenatrix, and Vallibonavenatrix.

<i>Atlanticopristis</i> Extinct genus of cartilaginous fishes

Atlanticopristis is an extinct genus of sclerorhynchid that lived during the Middle Cretaceous (Cenomanian) of what is now the Northeast Region of Brazil, between 100.5 and 93.9 million years ago. Fourteen fossil teeth from Atlanticopristis were found in the Alcântara Formation, and referred to the closely related Onchopristis in 2007; a redescription in 2008 by Brazilian paleontologists Manuel Medeiros and Agostinha Pereira assigned it to a new genus containing one species, Atlanticopristis equatorialis.

<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.

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

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

<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.

References

  1. 1 2 3 4 5 6 7 8 9 Medeiros, Manuel Alfredo; Lindoso, Rafael Matos; Mendes, Ighor Dienes; Carvalho, Ismar de Souza (August 2014). "The Cretaceous (Cenomanian) continental record of the Laje do Coringa flagstone (Alcântara Formation), northeastern South America". Journal of South American Earth Sciences. 53: 50–58. Bibcode:2014JSAES..53...50M. doi:10.1016/j.jsames.2014.04.002. ISSN   0895-9811.
  2. ↑ "GSA Geologic Time Scale". The Geological Society of America. Archived from the original on 2019-01-20. Retrieved 2018-06-13.
  3. ↑ Elias, Felipe; Bertini, Reinaldo; Alfredo Araújo Medeiros, Manuel (December 2007). "Pterosaur teeth from the Laje do Coringa, middle Cretaceous, São Luís-Grajaú basin, Maranhão state, Northern-Northeastern Brazil". Revista Brasileira de Geociências. 37 (4): 668–676. doi: 10.25249/0375-7536.20073744760668676 .
  4. ↑ Catuneanu, O; Khalifa, M.A; Wanas, H.A (August 2006). "Sequence stratigraphy of the Lower Cenomanian Bahariya Formation, Bahariya Oasis, Western Desert, Egypt". Sedimentary Geology. 190 (1–4): 121–137. Bibcode:2006SedG..190..121C. doi:10.1016/j.sedgeo.2006.05.010. ISSN   0037-0738.
  5. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 Kellner, Alexander W. A.; Azevedo, Sergio A. K.; Machado, Elaine B.; Carvalho, Luciana B.; Henriques, Deise D. R. (2011). "A new dinosaur (Theropoda, Spinosauridae) from the Cretaceous (Cenomanian) Alcântara Formation, Cajual Island, Brazil" (PDF). Anais da Academia Brasileira de Ciências. 83 (1): 99–108. doi: 10.1590/S0001-37652011000100006 . ISSN   0001-3765. PMID   21437377.
  6. 1 2 3 Janeiro, Priscila Bessa, iG Rio de (March 2011). "Museu Nacional anuncia descoberta de maior dinossauro brasileiro – Ciência – iG". Último Segundo (in Brazilian Portuguese). Retrieved 2018-06-12.{{cite news}}: CS1 maint: multiple names: authors list (link)
  7. ↑ Medeiros, Manuel; Carvalho Freire, Pedro; Pereira, Agostinha; Anderson Barros Santos, Ronny; Lindoso, Rafael; Flávia Amaral Coêlho, Ana; Brandão Passos, Emanuel; Sousa Melo Júnior, Emilio (2007). Paleontologia: Cenários De Vida. Vol. 1. Editora Interciência. pp. 413–423. ISBN   9788571931848.
  8. ↑ Martill, D. M.; Cruickshank, A. R. I.; Frey, E.; Small, P. G.; Clarke, M. (1996). "A new crested maniraptoran dinosaur from the Santana Formation (Lower Cretaceous) of Brazil" (PDF). Journal of the Geological Society. 153 (1): 5–8. Bibcode:1996JGSoc.153....5M. doi:10.1144/gsjgs.153.1.0005. S2CID   131339386.
  9. ↑ Kellner, A. W. A.; Campos, D. A. (1996). "First Early Cretaceous theropod dinosaur from Brazil with comments on Spinosauridae". Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen. 199 (2): 151–166. doi:10.1127/njgpa/199/1996/151.
  10. 1 2 3 4 Hone, David William Elliott; Holtz, Thomas Richard (June 2017). "A century of spinosaurs – a review and revision of the Spinosauridae with comments on their ecology". Acta Geologica Sinica - English Edition. 91 (3): 1120–1132. Bibcode:2017AcGlS..91.1120H. doi:10.1111/1755-6724.13328. ISSN   1000-9515. S2CID   90952478.
  11. ↑ Bertin, Tor (2010). "A catalogue of material and review of the Spinosauridae". PalArch's Journal of Vertebrate Palaeontology. 7 (4): 1–39.
  12. ↑ Phillips, Dom (September 2018). "Brazil museum fire: 'incalculable' loss as 200-year-old Rio institution gutted". The Guardian. Retrieved 2018-09-03.
  13. ↑ Lopes, Reinaldo José (September 2018). "Entenda a importância do acervo do Museu Nacional, destruído pelas chamas no RJ". Folha de S.Paulo (in Brazilian Portuguese). Retrieved 2018-09-03.
  14. ↑ Mortimer, M. "Megalosauroidea". theropoddatabase.com. Retrieved 2018-11-06.
  15. 1 2 3 "Museu Nacional anuncia descoberta do maior dinossauro carnívoro do Brasil – Notícias – Ciência". Ciência (in Brazilian Portuguese). Retrieved 2018-06-12.
  16. 1 2 3 "Pictures: New Dinosaur, Crocodile Cousin Found in Brazil". National Geographic. March 2011. Archived from the original on March 31, 2011. Retrieved 2018-06-12.
  17. ↑ Medeiros and Schultz, (2002). A fauna dinossauriana da Laje do Coringa, Cretáceo médio do Nordeste do Brasil. Arquivos do Museu Nacional. 60(3), 155-162.
  18. ↑ dal Sasso, C.; Maganuco, S.; Buffetaut, E.; Mendez, M.A. (2005). "New information on the skull of the enigmatic theropod Spinosaurus, with remarks on its sizes and affinities". Journal of Vertebrate Paleontology. 25 (4): 888–896. doi:10.1671/0272-4634(2005)025[0888:NIOTSO]2.0.CO;2. ISSN   0272-4634. S2CID   85702490.
  19. ↑ Grillo, O. N.; Delcourt, R. (2016). "Allometry and body length of abelisauroid theropods: Pycnonemosaurus nevesi is the new king". Cretaceous Research. 69: 71–89. doi:10.1016/j.cretres.2016.09.001.
  20. 1 2 3 Milner, Andrew; Kirkland, James (September 2007). "The case for fishing dinosaurs at the St. George Dinosaur Discovery Site at Johnson Farm". Utah Geological Survey Notes. 39: 1–3.
  21. 1 2 3 4 5 Sales, M. A. F.; Schultz, C. L. (2017). "Spinosaur taxonomy and evolution of craniodental features: Evidence from Brazil". PLOS ONE. 12 (11): e0187070. Bibcode:2017PLoSO..1287070S. doi: 10.1371/journal.pone.0187070 . PMC   5673194 . PMID   29107966.
  22. ↑ Medeiros, M. A. (2006). "Large theropod teeth from the Eocenomanian of northeastern Brazil and the occurrence of Spinosauridae". Revista Brasileira de Paleontologia. 9 (3): 333–338. doi: 10.4072/rbp.2006.3.08 .
  23. ↑ Buffetaut, Eric; Ouaja, Mohamed (2002). "A new specimen of Spinosaurus (Dinosauria, Theropoda) from the Lower Cretaceous of Tunisia, with remarks on the evolutionary history of the Spinosauridae". Bulletin de la Société Géologique de France. 173 (5): 415–421. doi:10.2113/173.5.415. hdl: 2042/216 . S2CID   53519187.
  24. ↑ Smyth, Robert S. H.; Ibrahim, Nizar; Martill, David M. (2020-05-23). "Sigilmassasaurus is Spinosaurus: a reappraisal of African spinosaurines". Cretaceous Research. 114: 104520. Bibcode:2020CrRes.11404520S. doi:10.1016/j.cretres.2020.104520. ISSN   0195-6671. S2CID   219487346.
  25. ↑ Toledo, Carlos E. V.; Sousa, Eliane P. de; Medeiros, Manuel A. A.; Bertini, Reinaldo J. (December 2011). "A new genus of dipnoiformes from the Cretaceous of Brazil". Anais da Academia Brasileira de Ciências. 83 (4): 1181–1192. doi: 10.1590/S0001-37652011000400006 . ISSN   0001-3765. PMID   22146953.
  26. ↑ Pereira, A. A.; Medeiros, M. A. (2008). "A new sclerorhynchiform (Elasmobranchii) from the middle Cretaceous of Brazil". Revista Brasileira de Paleontologia. 11 (3): 207–212. doi: 10.4072/rbp.2008.3.07 .
  27. ↑ Lindoso, Rafael Matos; Medeiros, Manuel Alfredo Araújo; Carvalho, Ismar de Souza; Pereira, Agostinha Araújo; Mendes, Ighor Dienes; Iori, Fabiano Vidoi; Sousa, Eliane Pinheiro; Arcanjo, Silvia Helena Souza; Silva, Taciane Costa Madeira (July 2019). "A new rebbachisaurid (Sauropoda: Diplodocoidea) from the middle Cretaceous of northern Brazil". Cretaceous Research. 104: 104191. Bibcode:2019CrRes.10404191L. doi:10.1016/j.cretres.2019.104191. ISSN   0195-6671. S2CID   201321631.
  28. ↑ Candeiro, Carlos Roberto A. (August 2015). "Middle Cretaceous dinosaur assemblages from northern Brazil and northern Africa and their implications for northern Gondwanan composition". Journal of South American Earth Sciences. 61: 147–153. Bibcode:2015JSAES..61..147C. doi:10.1016/j.jsames.2014.10.005. ISSN   0895-9811.
  29. ↑ Arden, Thomas M.S.; Klein, Catherine; Zouhri, Samir; Longrich, Nicholas R. (2018). "Aquatic adaptation in the skull of carnivorous dinosaurs (Theropoda: Spinosauridae) and the evolution of aquatic habits in spinosaurus". Cretaceous Research. 93: 275–284. doi:10.1016/j.cretres.2018.06.013. S2CID   134735938. Archived from the original on 2018-10-23. Retrieved 2018-10-22.
  30. ↑ Amiot, R.; Buffetaut, E.; Lécuyer, C.; Wang, X.; Boudad, L.; Ding, Z.; Fourel, F.; Hutt, S.; Martineau, F.; Medeiros, A.; Mo, J.; Simon, L.; Suteethorn, V.; Sweetman, S.; Tong, H.; Zhang, F.; Zhou, Z. (2010). "Oxygen isotope evidence for semi-aquatic habits among spinosaurid theropods". Geology. 38 (2): 139–142. Bibcode:2010Geo....38..139A. doi:10.1130/G30402.1.

This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.