Batrachotomus
Encyclopedia
Batrachotomus is a genus of prehistoric archosaur
. Fossils of this animal have been found in southern Germany
and dated from the Ladinian stage
of Middle Triassic
period, around 228 to 231 million years ago. Batrachotomus was described by palaeontologist David J. Gower
22 years after its discovery.
The locality where Batrachotomus lived was a swampy region and the name comes from the Greek
batrachos/βάτραχος (frog) and tome/τομή (cutting, slicing), which refers to its preying on the large amphibian Mastodonsaurus
. In contrast with sprawling reptiles, like crocodiles, this large carnivore was very agile with locomotor superiority due to its erect stance. A remarkable feature seen on its back was a row of paired, flattened bony plates. Batrachotomus was possibly an early relative of Postosuchus
, which lived during the dawn of the dinosaurs.
Batrachotomus was a heavily built, large quadrupedal reptile reaching 6 metres (19.7 ft) in length. A trait that characterized Batrachotomus, compared to other crurotarsans, was a series of paired small plates on its back which were attached to each vertebra. These bony deposits forming scales are called osteoderms. Flattened and leaf-shaped, these extended from behind the head along the column and reducing in size, ended at the tail. There is also evidence that osteoderms were present on the ventral region of the tail, as seen in Ticinosuchus ferox
, and even on the flank, belly and limbs.
Like other rauisuchians, Batrachotomus walked with an erect posture, although the limbs were not located directly under the trunk. The limbs were not equal in length as the forelimbs were about 70% of the hindlimbs. The toe bones (phalanges) are poorly preserved and the only well known bone is a fifth metatarsal (bone in hindlimbs attached to the toe bones) which was hooked in shape. However, hypotheses suggest that probably each forelimb had four toes and each hindlimb five.
Batrachotomus had a tall and narrow skull estimated at 40 to 50 cm (1.3 to 1.6 ft) in length. It had five pairs of fenestrae (skull openings), two pairs of which were for the eyes (called orbits
) and the nostril
s. Behind the orbits were two temporal fenestrae. These holes probably helped to reduce the weight of the skull and enabled the jaw to open more widely. As a typical archosaur, Batrachotomus had two antorbital fenestra
e between the orbits and nostrils, and a fifth pair of small openings at the rear part of the lower jaw.
The jaws contained sharp teeth which were compressed laterally and unequal in size and shape, and this variation of tooth shape is known as heterodonty. The teeth on the premaxilla
e (bones at the very tip of the upper jaw) were slender, unlike those of the maxilla
e (the main tooth-bearing bones in the upper jaw) which had a straight posterior edge. The upper jaw bore 30 teeth, with each premaxilla carrying about 4 teeth and each maxilla 11, while the lower jaw held 22 teeth.
Remains of Batrachotomus have been found in southern Germany, mainly in the Kupferzell
fossil locality in northern Baden-Württemberg
. Fossil collector
Johann G. Wegele discovered the first specimens in a 1977 excavation at the Erfurt Formation, dated from the Longobardian (late Ladinian) age. Other remains attributed to Batrachotomus have been collected in Vellberg-Eschenau, about 10 km east of Schwäbisch Hall
, and in Crailsheim
. The most notable are from Vellberg-Eschenau, which are represented by well preserved ribs and vertebrae (MHI 1895), and evidence of forelimbs and hindlimbs (SMNS 90018). Batrachotomus today is displayed in the Muschelkalk Museum, Ingelfingen
, Stuttgart
.
The fossils recovered from a marlstone remained undescribed until 1999 and palaeontologists referred to the genus simply as "rauisuchid" or "Kupferzellia". In 1999, palaeontologist David J. Gower described the holotype
(SMNS 52970) from the 1977 excavation, which is the largest specimen of the genus, comprised by incomplete skull and postcranial materials. Anatomy of the braincase (SMNS 80260) was made three years later, shedding light on the evolutionary relationships of the poorly known group of Rauisuchia. In 2009, Gower and Rainer R. Schoch reported a detailed reconstruction of the postcranial skeleton for the first time.
, a member of a family of carnivorous archosaurs within the larger group Rauisuchia
. The family name "Prestosuchidae" was established in 1966 by American paleontologist Alfred Romer
. Prestosuchids were quadrupedal reptiles, medium to large in size, characterized by erect posture, large and narrow skull and large antorbital openings
. Other genera of the family include: Karamuru
, Ticinosuchus
, Saurosuchus
and the type genus
Prestosuchus
.
Attention was first brought to Batrachotomus in 1993 by Michael Parrish, a palaeontologist at Northern Illinois University
. Parrish hypothesized that Batrachotomus (then "Kupferzellia") belonged to the family of Rauisuchidae
, another clade of carnivorous reptiles, and species of Rauisuchus
. However, the description of the braincase and a revisited cladistic analysis by Benton
and Walker
, showing the close relationships between Batrachotomus and Prestosuchus, led to the transfer of Batrachotomus to the family Prestosuchidae.
and Mastodonsaurus, and even animals like nothosaur
s and the distinct marine reptile
Tanystropheus
. Flora of the locality consisted of horsetail
s, fern
s, cycad
s and conifers, suggesting that there was rich vegetation.
Archosaur
Archosaurs are a group of diapsid amniotes whose living representatives consist of modern birds and crocodilians. This group also includes all extinct non-avian dinosaurs, many extinct crocodilian relatives, and pterosaurs. Archosauria, the archosaur clade, is a crown group that includes the most...
. Fossils of this animal have been found in southern Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
and dated from the Ladinian stage
Ladinian
The Ladinian is a stage and age in the Middle Triassic series or epoch. It spans the time between 237 ± 2 Ma and 228 ± 2 Ma...
of Middle Triassic
Middle Triassic
In the geologic timescale, the Middle Triassic is the second of three epochs of the Triassic period or the middle of three series in which the Triassic system is divided. It spans the time between 245 ± 1.5 Ma and 228 ± 2 Ma...
period, around 228 to 231 million years ago. Batrachotomus was described by palaeontologist David J. Gower
David J. Gower
David J. Gower is a palaeontologist.Since 2004 he is a herpetology researcher at the Museum of Natural History in London.-External links:* *...
22 years after its discovery.
The locality where Batrachotomus lived was a swampy region and the name comes from the Greek
Greek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...
batrachos/βάτραχος (frog) and tome/τομή (cutting, slicing), which refers to its preying on the large amphibian Mastodonsaurus
Mastodonsaurus
Mastodonsaurus was a large-headed temnospondyl that belonged to a group of advanced, mostly Triassic amphibians called capitosaurids. It was a giant among the stegocephalians and the largest animal of its time...
. In contrast with sprawling reptiles, like crocodiles, this large carnivore was very agile with locomotor superiority due to its erect stance. A remarkable feature seen on its back was a row of paired, flattened bony plates. Batrachotomus was possibly an early relative of Postosuchus
Postosuchus
Postosuchus, meaning "crocodile from Post ", was a basal archosaur that lived in what is now North America during the middle through to the late Triassic period...
, which lived during the dawn of the dinosaurs.
Description
Ticinosuchus
Ticinosuchus is an extinct genus of rauisuchian archosaur from the Middle Triassic of Switzerland and Italy.Ticinosuchus was about long, and its whole body, even the belly, was covered in thick, armoured scutes. The structure of the hips shows that its legs were placed under the body almost...
, and even on the flank, belly and limbs.
Like other rauisuchians, Batrachotomus walked with an erect posture, although the limbs were not located directly under the trunk. The limbs were not equal in length as the forelimbs were about 70% of the hindlimbs. The toe bones (phalanges) are poorly preserved and the only well known bone is a fifth metatarsal (bone in hindlimbs attached to the toe bones) which was hooked in shape. However, hypotheses suggest that probably each forelimb had four toes and each hindlimb five.
Batrachotomus had a tall and narrow skull estimated at 40 to 50 cm (1.3 to 1.6 ft) in length. It had five pairs of fenestrae (skull openings), two pairs of which were for the eyes (called orbits
Orbit (anatomy)
In anatomy, the orbit is the cavity or socket of the skull in which the eye and its appendages are situated. "Orbit" can refer to the bony socket, or it can also be used to imply the contents...
) and the nostril
Nostril
A nostril is one of the two channels of the nose, from the point where they bifurcate to the external opening. In birds and mammals, they contain branched bones or cartilages called turbinates, whose function is to warm air on inhalation and remove moisture on exhalation...
s. Behind the orbits were two temporal fenestrae. These holes probably helped to reduce the weight of the skull and enabled the jaw to open more widely. As a typical archosaur, Batrachotomus had two antorbital fenestra
Antorbital fenestra
An antorbital fenestra is an opening in the skull, in front of the eye sockets. This skull formation first appeared in archosaurs during the Triassic Period. Living birds today possess antorbital fenestrae, but the feature has been lost in modern crocodilians...
e between the orbits and nostrils, and a fifth pair of small openings at the rear part of the lower jaw.
The jaws contained sharp teeth which were compressed laterally and unequal in size and shape, and this variation of tooth shape is known as heterodonty. The teeth on the premaxilla
Premaxilla
The incisive bone is the portion of the maxilla adjacent to the incisors. It is a pair of small cranial bones at the very tip of the jaws of many animals, usually bearing teeth, but not always. They are connected to the maxilla and the nasals....
e (bones at the very tip of the upper jaw) were slender, unlike those of the maxilla
Maxilla
The maxilla is a fusion of two bones along the palatal fissure that form the upper jaw. This is similar to the mandible , which is also a fusion of two halves at the mental symphysis. Sometimes The maxilla (plural: maxillae) is a fusion of two bones along the palatal fissure that form the upper...
e (the main tooth-bearing bones in the upper jaw) which had a straight posterior edge. The upper jaw bore 30 teeth, with each premaxilla carrying about 4 teeth and each maxilla 11, while the lower jaw held 22 teeth.
Discovery and history
Kupferzell
Kupferzell is a town in the district of Hohenlohe in Baden-Württemberg, Germany. The largest neighbouring towns are Künzelsau and Schwäbisch Hall . The town is named after the Kupfer river that flows through it....
fossil locality in northern Baden-Württemberg
Baden-Württemberg
Baden-Württemberg is one of the 16 states of Germany. Baden-Württemberg is in the southwestern part of the country to the east of the Upper Rhine, and is the third largest in both area and population of Germany's sixteen states, with an area of and 10.7 million inhabitants...
. Fossil collector
Fossil collecting
Fossil collecting is the collection of fossils for scientific study, hobby, or profit. Fossil collecting, as practiced by amateurs, is the predecessor of modern paleontology and many still collect fossils and study fossils as amateurs...
Johann G. Wegele discovered the first specimens in a 1977 excavation at the Erfurt Formation, dated from the Longobardian (late Ladinian) age. Other remains attributed to Batrachotomus have been collected in Vellberg-Eschenau, about 10 km east of Schwäbisch Hall
Schwäbisch Hall
Schwäbisch Hall is a town in the German state of Baden-Württemberg and capital of the district of Schwäbisch Hall. The town is located in the valley of the river Kocher in the north-eastern part of Baden-Württemberg....
, and in Crailsheim
Crailsheim
Crailsheim is a town in the German state of Baden-Württemberg, 32 km east of Schwäbisch Hall, 40 km southwest of Ansbach in the Schwäbisch Hall district, incorporated in 1338....
. The most notable are from Vellberg-Eschenau, which are represented by well preserved ribs and vertebrae (MHI 1895), and evidence of forelimbs and hindlimbs (SMNS 90018). Batrachotomus today is displayed in the Muschelkalk Museum, Ingelfingen
Ingelfingen
Ingelfingen is a town in the Hohenlohe district, in Baden-Württemberg, Germany. It is situated on the river Kocher, 4 km northwest of Künzelsau, and 36 km northeast of Heilbronn....
, Stuttgart
Stuttgart (region)
Stuttgart is one of the four administrative districts of Baden-Württemberg, Germany, located in the north-east of the state of Baden-Württemberg, in the southwestern part of Germany.It is sub-divided into the three regions Heilbronn-Franken, Ostwürttemberg, Stuttgart.- External links :*...
.
The fossils recovered from a marlstone remained undescribed until 1999 and palaeontologists referred to the genus simply as "rauisuchid" or "Kupferzellia". In 1999, palaeontologist David J. Gower described the holotype
Holotype
A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...
(SMNS 52970) from the 1977 excavation, which is the largest specimen of the genus, comprised by incomplete skull and postcranial materials. Anatomy of the braincase (SMNS 80260) was made three years later, shedding light on the evolutionary relationships of the poorly known group of Rauisuchia. In 2009, Gower and Rainer R. Schoch reported a detailed reconstruction of the postcranial skeleton for the first time.
Classification
Batrachotomus was a prestosuchidPrestosuchidae
Prestosuchids were a group of Triassic carnivorous archosaurs. They were large active terrestrial apex predators, ranging from around in length. They succeeded the Erythrosuchidae as the largest archosaurs of their time...
, a member of a family of carnivorous archosaurs within the larger group Rauisuchia
Rauisuchia
Rauisuchia is a group of predatory and mostly large Triassic archosaurs. As a clade, Rauisuchia includes these Triassic forms and all crocodylomorphs, which are descendants of Triassic rauisuchians. The group in its traditional sense is paraphyletic, because it does not include crocodylomorph...
. The family name "Prestosuchidae" was established in 1966 by American paleontologist Alfred Romer
Alfred Romer
Alfred Sherwood Romer was an American paleontologist and comparative anatomist and a specialist in vertebrate evolution.-Biography:...
. Prestosuchids were quadrupedal reptiles, medium to large in size, characterized by erect posture, large and narrow skull and large antorbital openings
Antorbital fenestra
An antorbital fenestra is an opening in the skull, in front of the eye sockets. This skull formation first appeared in archosaurs during the Triassic Period. Living birds today possess antorbital fenestrae, but the feature has been lost in modern crocodilians...
. Other genera of the family include: Karamuru
Karamuru
Karamuru is a genus of prestosuchid archosaur from the Middle Triassic-age Santa Maria Formation of Brazil. It was found in the Paleorrota geopark. It is based on remains that had been assigned to Prestosuchus chininiquensis, including a nearly complete skull...
, Ticinosuchus
Ticinosuchus
Ticinosuchus is an extinct genus of rauisuchian archosaur from the Middle Triassic of Switzerland and Italy.Ticinosuchus was about long, and its whole body, even the belly, was covered in thick, armoured scutes. The structure of the hips shows that its legs were placed under the body almost...
, Saurosuchus
Saurosuchus
Saurosuchus is an extinct genus of rauisuchian archosaur in the family Prestosuchidae. With a length of around 7 m , it was the largest rauisuchian, except perhaps for the less well known Fasolasuchus. Like other rauisuchians, Saurosuchus walked on four fully erect limbs...
and 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...
Prestosuchus
Prestosuchus
Prestosuchus is an extinct genus of a group of rauisuchians called prestosuchids. Friedrich von Huene named the genus in honor of Vicentino Prestes de Almeida....
.
Attention was first brought to Batrachotomus in 1993 by Michael Parrish, a palaeontologist at Northern Illinois University
Northern Illinois University
Northern Illinois University is a state university and research institution located in DeKalb, Illinois, with satellite centers in Hoffman Estates, Naperville, Rockford, and Oregon. It was originally founded as Northern Illinois State Normal School on May 22, 1895 by Illinois Governor John P...
. Parrish hypothesized that Batrachotomus (then "Kupferzellia") belonged to the family of Rauisuchidae
Rauisuchidae
Rauisuchidae is a group of large predatory Triassic archosaurs, and constitute advanced representatives of the larger group Rauisuchia. There is some disagreement over which genera should be included in the Prestosuchidae, which in Rauisuchidae, and which in the Poposauridae, and indeed whether...
, another clade of carnivorous reptiles, and species of Rauisuchus
Rauisuchus
Rauisuchus was a basal archosaur which lived in what is now the Geopark of Paleorrota, Brazil, during the middle Triassic period . Named after fossil collector Dr. Wilhelm Rau, Rauisuchus belonged to a group of land-dwelling relatives to crocodiles...
. However, the description of the braincase and a revisited cladistic analysis by Benton
Michael J. Benton
Michael J. Benton is a British paleontologist, a Fellow of the Royal Society of Edinburgh, and professor of vertebrate palaeontology in the Department of Earth Sciences at the University of Bristol....
and Walker
Alick Walker
Alick Donald Walker was a British palaeontologist, after whom the Alwalkeria genus of dinosaur is named....
, showing the close relationships between Batrachotomus and Prestosuchus, led to the transfer of Batrachotomus to the family Prestosuchidae.
Paleoecology
Since 1977, the rich vertebrate fauna found at Baden-Württemberg reflect a moist region of the Middle Triassic in Germany. Along with Batrachotomus, palaeontologists recovered remains of fishes, amphibians, such as GerrothoraxGerrothorax
Gerrothorax is an extinct genus of temnospondyl amphibian from the Triassic period of Greenland, Germany, Sweden, and possibly Thailand. It is known from a single species, G. pulcherrimus, although several other species such as G. pustuloglomeratus have been named in the past.Gerrothorax was about...
and Mastodonsaurus, and even animals like nothosaur
Nothosaur
Nothosaurs were Triassic marine sauropterygian reptiles that may have lived like seals of today, catching food in water but coming ashore on rocks and beaches. They averaged about in length, with a long body and tail. The feet were paddle-like, and are known to have been webbed in life, to help...
s and the distinct marine reptile
Marine reptile
Marine reptiles are reptiles which have become secondarily adapted for an aquatic or semi-aquatic life in a marine environment.The earliest marine reptiles arose in the Permian period during the Paleozoic era...
Tanystropheus
Tanystropheus
Tanystropheus , was a 6 metre long reptile that dated from the Middle Triassic period. It is recognisable by its extremely elongated neck, which measured 3 metres long - longer than its body and tail combined. Despite this length, it had only ten neck vertebrae, each quite long...
. Flora of the locality consisted of horsetail
Horsetail
Equisetum is the only living genus in the Equisetaceae, a family of vascular plants that reproduce by spores rather than seeds.Equisetum is a "living fossil", as it is the only living genus of the entire class Equisetopsida, which for over one hundred million years was much more diverse and...
s, fern
Fern
A fern is any one of a group of about 12,000 species of plants belonging to the botanical group known as Pteridophyta. Unlike mosses, they have xylem and phloem . They have stems, leaves, and roots like other vascular plants...
s, cycad
Cycad
Cycads are seed plants typically characterized by a stout and woody trunk with a crown of large, hard and stiff, evergreen leaves. They usually have pinnate leaves. The individual plants are either all male or all female . Cycads vary in size from having a trunk that is only a few centimeters...
s and conifers, suggesting that there was rich vegetation.