Cristatusaurus

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Cristatusaurus
Temporal range: Early Cretaceous (Albian–Aptian),
~112  Ma
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Cristatusaurus skeletal by PaleoGeek.png
Diagram illustrating possible size and skeletal reconstruction combining several fossil specimens
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Saurischia
Clade: Theropoda
Family:† Spinosauridae
Subfamily:† Baryonychinae
Genus:† Cristatusaurus
Taquet and Russell, 1998
Species:
†C. lapparenti
Binomial name
†Cristatusaurus lapparenti
Synonyms

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.

Contents

Originally proposed to be an indeterminate species of Baryonyx , the identity of Cristatusaurus has been subject to debate, in part due to the fragmentary nature of its fossils. Some argue that it is probably the same dinosaur as Suchomimus, which has also been found in Niger, in the same sediment layers. In that case the genus Cristatusaurus would have priority, since it was named two months earlier. Others have concluded, however, that Cristatusaurus is a nomen dubium , considering it indistinguishable from both Suchomimus and Baryonyx. Some distinctions between the fossils of Cristatusaurus and Suchomimus have been pointed out, but it is uncertain whether these differences separate the two genera or if they are due to ontogeny (changes in an organism during growth). A recent study differentiated Cristatusaurus from Suchomimus and assigned it as a valid spinosaurid genus, placing the theropod just outside Baryonychinae.

History of research

Holotype specimen (MNHN GDF 366), consisting of jaw fossils, Museum national d'Histoire naturelle, Paris Cristatusaurus lapparenti fragments.JPG
Holotype specimen (MNHN GDF 366), consisting of jaw fossils, Muséum national d'Histoire naturelle, Paris

The first fossils of Cristatusaurus were found in 1973 by French paleontologist Philippe Taquet at Gadoufaoua, a locality within the Elrhaz Formation in Niger. The holotype specimen, cataloged under the number MNHN GDF 366, consists of two premaxillae (frontmost snout bones), a partial right maxilla (main upper jaw bone), and a dentary fragment from the mandible. Several paratypes have been assigned: MNHN GDF 365, a snout of two articulated premaxillae; as well as MNHN GDF 357, 358, 359 and 361, four dorsal vertebrae. [1] [2] Two thumb claws from separate specimens were also subsequently attributed to Cristatusaurus. [3] In 1984, the premaxilla specimens MNHN GDF 365 and 366 were first described in detail by Taquet, where he referred them to an unnamed new theropod within the family Spinosauridae, because of shared characteristics with the holotype dentary of Spinosaurus aegyptiacus. [1] At the time Taquet believed these specimens belonged to the creature's lower jaw, since no theropod was known then with over five teeth in the premaxilla, while Cristatusaurus had seven. This was later proven incorrect in 1996 by Brazilian paleontologists Alexander Kellner and Diogenes Campos, in light of the discoveries of other spinosaurids preserving upper jaw tips with over five teeth. [1] [4]

Referred claw, Museum national d'Histoire naturelle, Paris Cristatusaurus claw.jpg
Referred claw, Muséum national d'Histoire naturelle, Paris

In a 1986 publication, British paleontologists Alan Charig and Angela Milner considered Taquet's jaw elements nearly indistinguishable from those of the spinosaurid Baryonyx walkeri ; which they were describing on the basis of a partial skeleton from the Barremian of the Weald Clay Formation, England. [5] A 1997 followup to this preliminary paper referred MNHN GDF 365 and 366 to an indeterminate Baryonyx species, regardless of their younger geological age. [6] In 1998, Taquet and American geologist Dale Russell used the bones to erect the new genus Cristatusaurus, with the type species being Cristatusaurus lapparenti. Its generic name is derived from the Latin crista (for "crest"), and refers to a sagittal crest on the snout. [2] The specific name honors the late French paleontologist Albert-Félix de Lapparent, due to his contributions to dinosaur-related discoveries in the Sahara. In the same paper, several skull and vertebral fossils from the Tademaït of Algeria were attributed to a new species of Spinosaurus called S. maroccanus, which was described and compared to Cristatusaurus. [2] Spinosaurus maroccanus is now considered by most paleontologists either a nomen dubium (name of uncertain application) [7] [8] [9] or one synonymous with S. aegyptiacus. [10] Two months after Taquet and Russel published their paper, another spinosaurid genus and species was named from the Erlhaz Formation, Suchomimus tenerensis. Its describers, the American paleontologist Paul Sereno and colleagues, agreed with Charig and Milner in that there was no distinction between the skull fossils of Baryonyx and Cristatusaurus; concluding that the latter was a nomen dubium. [10] In a 2003 analysis, German paleontologist Oliver Rauhut concurred with this. [9]

Suchomimus skull Museum of Anchient Life.jpg
Baryonix skull 43553.JPG
The fragmentary Cristatusaurus skull material might represent the same taxon as Suchomimus (top) or Baryonyx (bottom)

When describing the taxon, Taquet and Russel based Cristatusaurus's separation from Baryonyx on the former's "brevirostrine condition of premaxilla" (having a short snout). [2] The meaning of this diagnosis has been considered obscure by various subsequent authors, who describe the specimens as almost identical to those of Baryonyx and Suchomimus. [11] In 2002, Eric Buffetaut and Mohamed Ouaja supported Cristatusaurus's junior synonymy with Baryonyx. [8] The same year, Hans-Dieter Sues and colleagues regarded both Cristatusaurus and Suchomimus as junior synonyms of Baryonyx, stating that there is no fossil evidence indicating more than one spinosaur lived in the Elrhaz Formation. [12] More recent research has retained Suchomimus and Baryonyx as distinct genera. [13] [14] [15] Others, such as Bertin Tor in 2010, and Carrano and colleagues in 2012, have referred to Cristatusaurus as an indeterminate baryonychine, because of how fragmentary its remains are. [11] [16]

In 2016, Christophe Hendrickx, Octávio Mateus, and Buffetaut noted that Taquet and Russel might have interpreted Cristatusaurus as having a shorter snout than Baryonyx by mistaking the notch where the maxillae articulated with the premaxillae for the nostril openings. Since both Suchomimus and Baryonyx have more completely preserved premaxillae, while Cristatusaurus only has the frontmost part of this bone known, Hendrickx and colleagues considered it possible that Cristatusaurus's snout was just as long as in Baryonyx. Therefore, they agreed with previous authors in the ambiguity of Taquet and Russel's diagnosis. Hendrickx and colleagues stated that since Cristatusaurus and Suchomimus are nearly identical and both hail from the same stratigraphic unit, they are almost certainly synonyms. The researchers found Cristatusaurus and Suchomimus similar in that they both had premaxillary crests, similar size ratio of tooth sockets, and shallow depressions in front of their nostril openings. However, since these features are minor and may vary within species as well as depending on age and sex, Hendrickx and colleagues did not identify any definitive autapomorphies (distinguishing features) of Cristatusaurus's holotype, and thus considered the taxon a nomen dubium until its postcranial remains are more closely examined. [17] Given that it was named first, Cristatusaurus lapparenti has priority over Suchomimus tenerensis in the case that they become synonymized. [18]

In a 2017 study, Marcos Sales and Cesar Schultz compared the holotype of Cristatusaurus (MNHN GDF 366) to the referred snout of Suchomimus (MNN GDF501). Both of them exhibit a narrow rim across the top of their premaxillae. However, Cristatusaurus's convex secondary palate is clearly visible in side view (situated under the premaxillary teeth), whereas in Suchomimus it is discernible only through cracks on the fossil snout. It was also pointed out that where known, the upward-sloping process of Cristatusaurus's maxilla is narrower than in Suchomimus. The researchers concluded that further study is needed to determine whether these differences are possible autapomorphies (distinguishing features) between the taxa, or if they are the result of ontogenetic (developmental) changes, given that the Cristatusaurus holotype represents a younger individual. [13] A 2021 study assigned Cristatusaurus just outside of Baryonychinae and differentiated from Suchomimus as a valid genus, supporting its independence as a genus. [19]

Description

Diagram showing the differences between an adult (A) and juvenile (B) Cristatusaurus premaxilla Cristatusaurus ontogeny by PaleoGeek.png
Diagram showing the differences between an adult (A) and juvenile (B) Cristatusaurus premaxilla

In 2012, American vertebrate paleontologist Thomas R. Holtz Jr. tentatively estimated Cristatusaurus at around 10 m (33 ft) in length and weighing between 1 and 4 tonnes (1.1 and 4.4 short tons). [20] [21] The holotype premaxillae are 115 mm (4.5 in) long and 55 mm (2.2 in) tall. The other known set of premaxillae (specimen MNHN GDF 365) are larger at 185 mm (7.3 in) long and 95 mm (3.7 in) tall. [4] The holotype's smaller size, smoother surface, and lack of co-ossified (fused) sutures all indicate that it belongs to a juvenile individual; while MNHN GDF 365 probably represents an adult. [4]

The tip of Cristatusaurus's premaxilla was short and expanded, while the rear end was narrowed near the suture with the maxilla; this rosette-like snout shape was characteristic of spinosaurids. The front of the upper jaw was concave on the bottom, shaped to interlock with what would have been the convex and also enlarged tip of the mandible's dentary bone. [2] [4] [22] A thin sagittal crest ran lengthwise on top of the premaxillae, a condition present in Baryonyx and Suchomimus, and very prominent in Angaturama (a possible synonym of Irritator ). [13] Like all spinosaurids, Cristatusaurus's external nares (bony nostrils) were positioned further back on the skull that in typical theropods. [4] [13] Two bony processes extended across the underside of the snout, in a convex structure that formed the animal's secondary palate. This condition is observed in all extant crocodilians, but not in most theropod dinosaurs; however, it was a common trait among spinosaurids. [13] [12]

Type premaxillae from reversed left side (A), bottom (B), and top (C) views Cristatusaurus premaxillae.png
Type premaxillae from reversed left side (A), bottom (B), and top (C) views

Cristatusaurus's dental alveoli (tooth sockets) were closely spaced, those in the maxilla and dentary were flattened somewhat sideways; while the ones in the premaxillae were large and mostly circular, with the frontmost alveoli being the largest. [2] [4] Partial tooth crowns preserved in some alveoli show that the teeth were finely serrated , with flutes (lengthwise ridges) on their lingual (inward-facing side of teeth) surface. [4] Both premaxilla specimens had seven alveoli on each side, the same number as in Suchomimus, Angaturama, Oxalaia , and the Spinosaurus maroccanus specimen. [2] [23]

One of the dorsal vertebrae (MNHN GDF 358) measured 13.5 cm (5.3 in) in centrum length, which is equal to the largest known vertebrae of Spinosaurus maroccanus. The preserved base of one of Cristatusaurus's vertebral neural spines (MNHN GDF 359) was 15 mm (0.59 in) thick in comparison to the 25 mm (0.98 in) measurement seen in an equivalent Spinosaurus vertebra, indicating that Cristatusaurus's neural spines were probably not as tall as those of Spinosaurus. [2] Of the two manual unguals (claws) referred to Cristatusaurus, one was equivalent in size to those found for Suchomimus and Baryonyx, while the other was about 25 to 30 percent smaller. [3] As a spinosaur, it would have wielded these claws with three-fingered hands carried by robust arms. [22]

Classification

Comparison between snout fossils of Suchomimus (A, B), Cristatusaurus (C, D), and Baryonyx (E) Suchomimus, Cristatusaurus, and Baryonyx rostra.png
Comparison between snout fossils of Suchomimus (A, B), Cristatusaurus (C, D), and Baryonyx (E)

Spinosaurids were large bipedal carnivores with well-built forelimbs and elongated, crocodile-like skulls. The taxonomic and phylogenetic affinities of the group are subject to active research and debate, given that in comparison to other theropod groups, many of the family's taxa (including Cristatusaurus) are based on relatively poor fossil material. [22] Traditionally the family has been divided into two subfamilies: Spinosaurinae, which includes genera like Irritator, Spinosaurus, and Oxalaia; and Baryonychinae, which includes Baryonyx and Suchomimus. Although the genus and species placement of Cristatusaurus lapparenti is disputed, its fossils certainly belong to a member of the baryonychinae, because of its more forwardly placed external nostrils; relatively larger first premaxillary teeth; and more closely spaced tooth sockets than in spinosaurines; as well as the presence of fine serrations, in contrast to spinosaurines lacking them entirely. [22] [12] [23] However, authors like Sales and Schultz have questioned the monophyly of Baryonychinae (meaning it might be an unnatural group), stating that the South American spinosaurids Angaturama and Irritator represent intermediate forms between Baryonychinae and Spinosaurinae, based on their craniodental (skull and tooth) features. Their cladogram can be seen below. [13]

Spinosauridae

Paleoecology

Outcrops of the Erlhaz Formation, (Gadoufaoua in lower right) Gadoufaoua.png
Outcrops of the Erlhaz Formation, (Gadoufaoua in lower right)

The Elrhaz Formation, part of the Tegama Group, consists mainly of fluvial sandstones with low relief, much of which is obscured by sand dunes. [24] [25] The sediments are coarse- to medium-grained, with almost no fine-grained horizons. [26] Cristatusaurus lived in what is now Niger, during the late Aptian to early Albian stages of the Early Cretaceous Period, 112 million years ago. [27] [28] The sediment layers of the formation have been interpreted as an inland habitat of extensive freshwater floodplains and fast-moving rivers, with a tropical climate that likely experienced seasonal dry periods. [27]

Hypothetical life restoration Cristatusaurus lapparenti by PaleoGeek.png
Hypothetical life restoration

This environment was home to a variety of fauna including dinosaurs, pterosaurs, chelonians, fish, hybodont sharks, and freshwater bivalves. [28] [25] Besides Cristatusaurus lapparenti and Suchomimus tenerensis, theropods such as the abelisaurid Kryptops palaios , the carcharodontosaurid Eocarcharia dinops and the noasaurid Afromimus tenerensis have been found. Herbivorous dinosaurs of the region included iguanodontians like Ouranosaurus nigeriensis , Elrhazosaurus nigeriensis , Lurdusaurus arenatus , and two sauropods: Nigersaurus taqueti , and an unnamed titanosaur. Crocodylomorphs were abundant; represented by the giant pholidosaur species Sarcosuchus imperator , as well as small notosuchians like Anatosuchus minor , Araripesuchus wegeneri , and Stolokrosuchus lapparenti . [25] The local flora probably consisted mainly of ferns, horsetails, and angiosperms, based on the dietary adaptations of the sauropods that lived there. [27]

A semiaquatic lifestyle has been proposed for many spinosaurids, on account of their unusual anatomical traits and bone histology. Cristatusaurus's teeth would have likely been used for piercing and gripping prey items, rather than slicing flesh, as indicated by their subcircular cross section and reduced serrations. Its teeth, combined with the sinusoidal (wave-like) curvature of the jaws, would have performed as tan efficient trap for fish. The retracted nostrils would have allowed it to submerge its snout further underwater than most theropods, while still being able to breathe; and the bony secondary palate is theorized to have reinforced the skull against bending stresses when feeding. The use of the giant recurved manual unguals of spinosaurs is still under debate; suggested functions have ranged from gaffing aquatic prey out of the water, to scavenging carcasses or digging. [4] [12] [13] [29]

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 stage of the Late Cretaceous period, about 100 to 94 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 type species is S. aegyptiacus from Egypt and Morocco. Although a potential second species, S. maroccanus, has been recovered from Morocco, this dubious species is likely a junior synonym of S. aegyptiacus. Other possible junior synonyms include Sigilmassasaurus from the Kem Kem beds in Morocco and Oxalaia from the Alcântara Formation in Brazil, though other researchers propose both genera to be a distinct taxon.

<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 age 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 Desert.

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

Ouranosaurus is a genus of herbivorous basal hadrosauriform dinosaur that lived during the Aptian stage of the Early Cretaceous of modern-day Niger and Cameroon. Ouranosaurus measured about 7–8.3 metres (23–27 ft) long and weighed 2.2 metric tons. Two rather complete fossils were found in the Elrhaz Formation, Gadoufaoua deposits, Agadez, Niger, in 1965 and 1970, with a third indeterminate specimen known from the Koum Formation of Cameroon. The animal was named in 1976 by French paleontologist Philippe Taquet; the type species being Ouranosaurus nigeriensis. The generic name is a combination of ourane, a word with multiple meanings, and sauros, the Greek word for lizard. The specific epithet nigeriensis alludes to Niger, its country of discovery. And so, Ouranosaurus nigeriensis could be interpreted as "brave lizard originating from Niger".

<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>Lurdusaurus</i> Extinct genus of dinosaurs

Lurdusaurus is a genus of massive and unusually shaped iguanodont dinosaur from the Elrhaz Formation in Niger. It contains one species, L. arenatus. The formation dates to the Early Cretaceous, roughly 112 million years ago. Lurdusaurus has a highly atypical body plan for an iguanodont, with a small skull, long neck, rotund torso, and powerful forelimbs and claws, somewhat reminiscent of a ground sloth. Its metacarpals are fused and reinforced into a large block, and the thumb spike is remarkably enormous. These would have allowed the hand to have functioned almost like a ball-and-chain flail. Lurdusaurus is estimated to have been 7–9 m (23–30 ft) long and 2 m high when on all-fours, but its stomach would have been only 70 cm off the ground. It may have weighed 2.5–5.5 t, conspicuously heavy for an iguanodontid this size.

<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>Elrhazosaurus</i> Extinct genus of dinosaurs

Elrhazosaurus is a genus of basal iguanodontian dinosaur, known from isolated bones found in Early Cretaceous rocks of Niger. These bones were initially thought to belong to a species of the related dryosaurid Valdosaurus, but have since been reclassified.

<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. One study suggested that this taxon is a junior synonym of the closely related African genus Spinosaurus, but this was disputed by subsequent studies which consider the genus to be diagnostic.

<i>Ichthyovenator</i> Genus of dinosaur

Ichthyovenator is a genus of spinosaurid dinosaur that lived in what is now Laos, sometime between 120 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 several spinosaurid taxa known from the Iberian peninsula, the others being Iberospinus, Protathlitis, Baryonyx, Riojavenatrix, and Vallibonavenatrix.

<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.

<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 potentially semi-aquatic lifestyle earlier in the evolution of this clade.

References

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