Spinosauridae
Encyclopedia
Spinosauridae is a family of specialised theropod dinosaur
s. Members of this family were large, bipedal predators with elongated, crocodile
-like skulls, sporting conical teeth with no or only very tiny serrations. The front dentary teeth fanned out, giving the animal a characteristic look. The name of this family alludes to the typically conspicuous sail-like structure protruding from the back of species in the type genus
, Spinosaurus
. The purpose of the sail is disputed, whereas popular explanations are that it may have served as a thermoregulator, a threat display, or as a sexual display during courtship, some palaeontologists rather interpret the neural spine elongation in Spinosaurus as a support of a muscular/fatty hump.
Spinosaurid fossil
s have been recovered in Africa
, Europe
, South America
, Asia
, and Australia
.
and became abundant in the Early Cretaceous
. So far, the Late Jurassic record of spinosaurids consists only of referred teeth, dating to 155 million years ago. They seem to have declined sharply in the Cenomanian
, and while teeth from the Turonian
of Argentina have been attributed to spinosaurid dinosaurs, but they recently turned out to be crurotarsan
teeth. Some are known to have persisted into the mid-Santonian
, represented by a single baryonychine tooth found in the Majiacun Formation
of Henan, China.
) have shown that they had a very different skull shape and construction compared to other large predatory dinosaurs like Allosaurus
and Tyrannosaurus
. In most predatory dinosaurs, the jaws were broad either in width, height, or both, while spinosaurid jaws were thin and narrow. This lead paleontologists like Sues, Frey and Martill to conclude that spinosaurids, unlike other theropods, were not specialized in attacking large, struggling prey.
Sues and colleagues studied the construction of the spinosaurid skull, and concluded that their mode of feeding was to use extremely quick, powerful strikes to seize small prey items with the jaws, employing the powerful neck muscles in rapid up and down motion. Due to the narrow snout, powerful side to side motion of the skull in prey capture is unlikely.
s), based on comparisons of their jaws with the jaws of modern crocodilia
ns. Rayfield and colleagues, in 2007, were the first to conduct actual biomechanical studies on a spinosaurid skull (using the European spinosaurid Baryonyx
). They found that the structure and bite force of baryonychine jaws was almost identical to modern gharial
s, supporting the idea that at least baryonychines were mainly fish-eaters, though the jaws of spinosaurines appear to have been more generalized.
Direct fossil evidence shows that spinosaurids fed on fish as well as a variety of other small to medium-sized animals, including small dinosaurs. Baryonyx was found with fish scales and the digested bones of a young Iguanodon
in its stomach cavity, and there is one documented example of a spinosaurid having eaten a pterosaur
. It is likely that spinosaurids were generalists
specializing in small prey of any kind, fish included.
ratios of spinosaurid bones indicates semiaquatic lifestyles. Isotope ratios from teeth from the spinosaurids Baryonyx, Irritator
, Siamosaurus
, and Spinosaurus were compared with isotopic compositions from contemporaneous theropods, turtles, and crocodilians. The study found that, among theropods, spinosaurid isotope ratios were closer to those of turtles and crocodilians. Siamosaurus specimens tended to have the largest difference from the ratios of other theropods, and Spinosaurus tended to be have the least difference. The authors concluded that spinosaurids, like modern crocodilians and hippopotamuses, spent much of their daily lives in water. The authors also suggested that semiaquatic habits and piscivory
in spinosaurids can explain how spinosaurids coexisted with other large theropods: by feeding on different prey items and living in different habitats, the different types of theropods would have been out of direct competition.
in 1915 to include the single genus Spinosaurus. The family was expanded as more close relatives of Spinosaurus were uncovered. The first cladistic definition of Spinosauridae was provided by Paul Sereno
in 1998 (as "All spinosaurids closer to Spinosaurus than to Torvosaurus
).
Spinosauridae contains two subfamilies—Spinosaurinae and Baryonychinae. The subfamily Spinosaurinae was named by Sereno in 1998, and defined by Holtz
et al. (2004) as all taxa closer to Spinosaurus aegyptiacus than to Baryonyx walkeri. The subfamily Baryonychinae was named by Charig
& Milner in 1986. They erected both the subfamily and the family Baryonychidae for the newly discovered Baryonyx, before it was referred to the Spinosauridae. Their subfamily was defined by Holtz et al. in 2004, as the complementary clade of all taxa closer to Baryonyx walkeri than to Spinosaurus aegyptiacus.
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...
s. Members of this family were large, bipedal predators with elongated, crocodile
Crocodile
A crocodile is any species belonging to the family Crocodylidae . The term can also be used more loosely to include all extant members of the order Crocodilia: i.e...
-like skulls, sporting conical teeth with no or only very tiny serrations. The front dentary teeth fanned out, giving the animal a characteristic look. The name of this family alludes to the typically conspicuous sail-like structure protruding from the back of species in the type genus
Type genus
In biological classification, a type genus is a representative genus, as with regard to a biological family. The term and concept is used much more often and much more formally in zoology than it is in botany, and the definition is dependent on the nomenclatural Code that applies:* In zoological...
, Spinosaurus
Spinosaurus
Spinosaurus is a genus of theropod dinosaur which lived in what is now North Africa, from the lower Albian to lower Cenomanian stages of the Cretaceous period, about 112 to 97 million years ago. This genus was first known from Egyptian remains discovered in 1912 and described by German...
. The purpose of the sail is disputed, whereas popular explanations are that it may have served as a thermoregulator, a threat display, or as a sexual display during courtship, some palaeontologists rather interpret the neural spine elongation in Spinosaurus as a support of a muscular/fatty hump.
Spinosaurid fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
s have been recovered in Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
, Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
, South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
, Asia
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...
, and Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
.
Evolutionary history
The first spinosaurids appeared during the Late JurassicLate Jurassic
The Late Jurassic is the third epoch of the Jurassic Period, and it spans the geologic time from 161.2 ± 4.0 to 145.5 ± 4.0 million years ago , which is preserved in Upper Jurassic strata. In European lithostratigraphy, the name "Malm" indicates rocks of Late Jurassic age...
and became abundant in the Early Cretaceous
Early Cretaceous
The Early Cretaceous or the Lower Cretaceous , is the earlier or lower of the two major divisions of the Cretaceous...
. So far, the Late Jurassic record of spinosaurids consists only of referred teeth, dating to 155 million years ago. They seem to have declined sharply in the Cenomanian
Cenomanian
The Cenomanian is, in the ICS' geological timescale the oldest or earliest age of the Late Cretaceous epoch or the lowest stage of the Upper Cretaceous series. An age is a unit of geochronology: it is a unit of time; the stage is a unit in the stratigraphic column deposited during the corresponding...
, and while teeth from the Turonian
Turonian
The Turonian is, in the ICS' geologic timescale, the second age in the Late Cretaceous epoch, or a stage in the Upper Cretaceous series. It spans the time between 93.5 ± 0.8 Ma and 89.3 ± 1 Ma...
of Argentina have been attributed to spinosaurid dinosaurs, but they recently turned out to be crurotarsan
Crurotarsi
The Crurotarsi are a group of archosauriformes, represented today by the crocodiles,...
teeth. Some are known to have persisted into the mid-Santonian
Santonian
The Santonian is an age in the geologic timescale or a chronostratigraphic stage. It is a subdivision of the Late Cretaceous epoch or Upper Cretaceous series. It spans the time between 85.8 ± 0.7 mya and 83.5 ± 0.7 mya...
, represented by a single baryonychine tooth found in the Majiacun Formation
Majiacun Formation
The Majiacun Formation is a Mesozoic geologic formation. Dinosaur remains are among the fossils that have been recovered from the formation.-See also:* List of dinosaur-bearing rock formations** List of stratigraphic units with few dinosaur genera...
of Henan, China.
Predatory behavior
Studies of spinosaurids (specifically of IrritatorIrritator
Irritator is a genus of spinosaurid dinosaur that lived in the early Cretaceous Period , around 110 million years ago. Current estimations indicate a length of 8 meters . It was found in Brazil...
) have shown that they had a very different skull shape and construction compared to other large predatory dinosaurs like Allosaurus
Allosaurus
Allosaurus is a genus of large theropod dinosaur that lived 155 to 150 million years ago during the late Jurassic period . The name Allosaurus means "different lizard". It is derived from the Greek /allos and /sauros...
and Tyrannosaurus
Tyrannosaurus
Tyrannosaurus meaning "tyrant," and sauros meaning "lizard") is a genus of coelurosaurian theropod dinosaur. The species Tyrannosaurus rex , commonly abbreviated to T. rex, is a fixture in popular culture. It lived throughout what is now western North America, with a much wider range than other...
. In most predatory dinosaurs, the jaws were broad either in width, height, or both, while spinosaurid jaws were thin and narrow. This lead paleontologists like Sues, Frey and Martill to conclude that spinosaurids, unlike other theropods, were not specialized in attacking large, struggling prey.
Sues and colleagues studied the construction of the spinosaurid skull, and concluded that their mode of feeding was to use extremely quick, powerful strikes to seize small prey items with the jaws, employing the powerful neck muscles in rapid up and down motion. Due to the narrow snout, powerful side to side motion of the skull in prey capture is unlikely.
Diet
Spinosaurids have in the past often been considered mainly fish-eaters (piscivorePiscivore
A piscivore is a carnivorous animal which eats primarily fish. Piscivory was the diet of early tetrapods , insectivory came next, then in time reptiles added herbivory....
s), based on comparisons of their jaws with the jaws of modern crocodilia
Crocodilia
Crocodilia is an order of large reptiles that appeared about 84 million years ago in the late Cretaceous Period . They are the closest living relatives of birds, as the two groups are the only known survivors of the Archosauria...
ns. Rayfield and colleagues, in 2007, were the first to conduct actual biomechanical studies on a spinosaurid skull (using the European spinosaurid Baryonyx
Baryonyx
Baryonyx is a genus of carnivorous saurischian dinosaur first discovered in clay pits just south of Dorking, England, and later reported from fossils found in northern Spain and Portugal. It is known to contain only one species, Baryonyx walkeri...
). They found that the structure and bite force of baryonychine jaws was almost identical to modern gharial
Gharial
The gharial , , also called Indian gavial or gavial, is the only surviving member of the once well-represented family Gavialidae, a long-established group of crocodilians with long, slender snouts...
s, supporting the idea that at least baryonychines were mainly fish-eaters, though the jaws of spinosaurines appear to have been more generalized.
Direct fossil evidence shows that spinosaurids fed on fish as well as a variety of other small to medium-sized animals, including small dinosaurs. Baryonyx was found with fish scales and the digested bones of a young Iguanodon
Iguanodon
Iguanodon is a genus of ornithopod dinosaur that lived roughly halfway between the first of the swift bipedal hypsilophodontids and the ornithopods' culmination in the duck-billed dinosaurs...
in its stomach cavity, and there is one documented example of a spinosaurid having eaten a pterosaur
Pterosaur
Pterosaurs were flying reptiles of the clade or order Pterosauria. They existed from the late Triassic to the end of the Cretaceous Period . Pterosaurs are the earliest vertebrates known to have evolved powered flight...
. It is likely that spinosaurids were generalists
Generalist and specialist species
A generalist species is able to thrive in a wide variety of environmental conditions and can make use of a variety of different resources . A specialist species can only thrive in a narrow range of environmental conditions or has a limited diet. Most organisms do not all fit neatly into either...
specializing in small prey of any kind, fish included.
Habitat
A 2010 publication by Romain Amiot and colleagues found that oxygen isotopeIsotopes of oxygen
There are three stable isotopes of oxygen that lead to oxygen having a standard atomic mass of 15.9994 u. 17 radioactive isotopes have also been characterized, with mass numbers from 12O to 28O, all short-lived, with the longest-lived being 15O with a half-life of 122.24 seconds...
ratios of spinosaurid bones indicates semiaquatic lifestyles. Isotope ratios from teeth from the spinosaurids Baryonyx, Irritator
Irritator
Irritator is a genus of spinosaurid dinosaur that lived in the early Cretaceous Period , around 110 million years ago. Current estimations indicate a length of 8 meters . It was found in Brazil...
, Siamosaurus
Siamosaurus
Siamosaurus is a genus of theropod dinosaur from Early Cretaceous Thailand. The size of the animal is unknown, but it may have reached a length of about 9.1 meters . The type species, Siamosaurus suteethorni, was formally described by Buffetaut and Ingavat in 1986...
, and Spinosaurus were compared with isotopic compositions from contemporaneous theropods, turtles, and crocodilians. The study found that, among theropods, spinosaurid isotope ratios were closer to those of turtles and crocodilians. Siamosaurus specimens tended to have the largest difference from the ratios of other theropods, and Spinosaurus tended to be have the least difference. The authors concluded that spinosaurids, like modern crocodilians and hippopotamuses, spent much of their daily lives in water. The authors also suggested that semiaquatic habits and piscivory
Piscivore
A piscivore is a carnivorous animal which eats primarily fish. Piscivory was the diet of early tetrapods , insectivory came next, then in time reptiles added herbivory....
in spinosaurids can explain how spinosaurids coexisted with other large theropods: by feeding on different prey items and living in different habitats, the different types of theropods would have been out of direct competition.
Taxonomy
The family Spinosauridae was named by Ernst StromerErnst Stromer
Ernst Freiherr Stromer von Reichenbach was a German paleontologist.He described the following Cretaceous dinosaurs from Egypt: Aegyptosaurus, Bahariasaurus, Carcharodontosaurus, and the largest known theropod, Spinosaurus aegyptiacus...
in 1915 to include the single genus Spinosaurus. The family was expanded as more close relatives of Spinosaurus were uncovered. The first cladistic definition of Spinosauridae was provided by Paul Sereno
Paul Sereno
Paul Callistus Sereno is an American paleontologist from the University of Chicago who discovered several new dinosaur species on several continents. He has conducted excavations at sites as varied as Inner Mongolia, Argentina, Morocco, and Niger...
in 1998 (as "All spinosaurids closer to Spinosaurus than to Torvosaurus
Torvosaurus
Torvosaurus is a genus of large theropod dinosaur that lived during the Late Jurassic period...
).
Spinosauridae contains two subfamilies—Spinosaurinae and Baryonychinae. The subfamily Spinosaurinae was named by Sereno in 1998, and defined by Holtz
Thomas R. Holtz Jr.
Thomas Richard Holtz, Jr., Ph.D. is a vertebrate palaeontologist and senior lecturer at the University of Maryland's Department of Geology. He has published extensively on the phylogeny, morphology, ecomorphology, and locomotion of terrestrial predators, especially on tyrannosaurids and other...
et al. (2004) as all taxa closer to Spinosaurus aegyptiacus than to Baryonyx walkeri. The subfamily Baryonychinae was named by Charig
Alan J. Charig
Alan Jack Charig was an English palaeontologist and writer who popularised his subject on television and in books at the start of the wave of interest in dinosaurs in the 1970s....
& Milner in 1986. They erected both the subfamily and the family Baryonychidae for the newly discovered Baryonyx, before it was referred to the Spinosauridae. Their subfamily was defined by Holtz et al. in 2004, as the complementary clade of all taxa closer to Baryonyx walkeri than to Spinosaurus aegyptiacus.
Classification
- Superfamily MegalosauroideaMegalosauroideaMegalosauroidea is a group of tetanuran theropod dinosaurs that lived from the Middle Jurassic to the Late Cretaceous period.-Classification:...
- Family Spinosauridae
-
- Siamosaurus suteethorni
- Subfamily Baryonychinae
- Baryonyx walkeri
- Cristatusaurus lapparenti
- Suchomimus tenerensis
- Suchosaurus cultridensSuchosaurusSuchosaurus is as a spinosaurid theropod dinosaur from Cretaceous England, originally believed to be a genus of crocodile. The type material consists of teeth. Two species, S. cultridens and S. girardi have been named, though the S. girardi material was reclassified by Buffetaut as Baryonyx...
- Subfamily Spinosaurinae
- Irritator challengeri
- Spinosaurus aegyptiacus
- Oxalaia quilombensis
-
- Family Spinosauridae
- Indeterminate Spinosauridae
- "SinopliosaurusSinopliosaurus (dinosaur)"Sinopliosaurus" is a spinosaurid theropod dinosaur from the Early Cretaceous of southern China, known only from teeth. It includes a single species, "S." fusuiensis, that was first assigned to the plesiosaur Sinopliosaurus. Because this species is not a plesiosaur and therefore is not within the...
" fusuiensis
- "Sinopliosaurus
External links
- Spinosauridae
- Spinosauridae on the Theropod Database