Stenopterygius
Encyclopedia
Stenopterygius is an extinct genus
of thunnosaur ichthyosaur
known from Europe
(England
, France
, Germany
, Luxembourg
and Switzerland
). Maximum length was 4 meters.
Most of the known specimens of Stenopterygius, more than 100, were recently redescribed by Michael W. Maisch. He found that S. quadriscissus (the type species) also includes S. eos, S. incessus and S. macrophasma, as well as specimens previously referred to S. hauffianus and S. megacephalus. Maisch followed Woodward (1932) and considered Ichthyosaurus
triscissus to be a valid species of Stenopterygius. The type specimens of S. longifrons, S. megacephalus, and S. megalorhinus were all referred to this species as the name I. triscissus has a priority over them. Some specimens previously referred to S. megalorhinus, as well as the holotype of S. cuneiceps, were found to belong to a species of their own for which the binomen Stenopterygius uniter can be used.
As the holotype of S. uniter was destroyed in World War II
, Maisch proposed a neotype. Maisch also found that S. promegacephalus is a nomen dubium
as it is based on juvenile specimen, and that the lectotype of S. hauffianus can be determined as Stenopterygius cf. S. quadriscissus at best, and therefore this species should be considered a nomen dubium
. He found out that most specimens previously referred to S. hauffianus can be referred to S. quadriscissus, while the rest belongs to a highly distinctive new taxon that can't be referred to any valid species of Stenopterygius. This species was reassigned to its own genus, Hauffiopteryx
.
Stenopterygius is known from the lectotype
GPIT 43/0219-1, articulate
d complete skeleton
which preserved a very large embryo. The animal is about 3.15 m (10.3 ft) in length. It was collected from the Harpoceras elegantulum-exaratum ammonoid subzones (more specifically Lias ε II3-4), Harpoceras falcifer zone, of the famous Posidonien-Schiefer lagerstätte
(Posidonia Shale
) of Holzmaden
, dating to the early Toarcian
stage of the Early Jurassic
, about 182 million years ago. Maisch referred to the type species 30 additional specimens, all came from Dobbertin of Mecklenburg-Vorpommern and Holzmaden
, Germany and Dudelange
, Luxembourg. They were collected from the Harpoceras palum to H. falciferum ammonoid subzones (Lias ε I2-II11, lower-middle early Toarcian), Harpoceras tenuicostatum-falcifer zones, of the Posidonia Shale. S. triscissus is known from the holotype
GPIT 12/0224-2, articulate
d almost complete skeleton
. The animal is a young adult about 2.1 m (6.9 ft) in length. It was collected from the Harpoceras exaratum-elegans ammonoid subzones (more specifically Lias ε II6), Harpoceras falcifer zone, of the Posidonia Shale
, in Ohmden
, dating to the middle Early Toarcian
stage of the Early Jurassic
. Maisch referred to this species 13 additional specimens, all came from various localities in England, France, Germany, Luxembourg and Switzerland. They were collected from the Lias ε II1-III, dating to the middle-late Early Toarcian. S. uniter is known from the holotype
SMNS 14216, articulated complete skeleton which was destroyed in World War II. The animal is an adult about 3.35 m (11 ft) in length. The proposed neotype is GPIT 1491/10, articulated almost complete skeleton. The animal is a young adult about 2.34 m (7.7 ft) in length. It was collected from the Harpoceras falcifer ammonoid subzones (more specifically Lias ε II10), Harpoceras falcifer zone, of the Posidonia Shale
, in Holzmaden
, dating to the middle Early Toarcian
stage of the Early Jurassic
. Maisch referred to this species 10 additional specimens, all came from Holzmaden. They were collected from the Harpoceras exaratum to H. falciferum ammonoid subzones (Lias ε II6-II11, middle early Toarcian), Harpoceras falcifer zones, of the Posidonia Shale.
Additional materials were described by Hannah Caine and Michael J. Benton
in 2011, from the early Toarcian of Strawberry Bank, Ilminster
of England. The specimens are all juveniles or infants which preserved mostly by almost complete skeletons and some skulls. They include BRLSI
M1405, BRLSI M1407, BRLSI M1408, BRLSI M1409. Caine and Benton referred these specimens to S. triscissus.
Maisch and Matzke (2000) and Maisch (2010) regarded Chacaicosaurus
and Hauffiopteryx
to be stenopterygiids. However, they didn't performed any cladistic analyses to confirm these claims. Fischer et al. (2011) performed a cladistic analysis that found Chacaicosaurus to be a basal
thunnosaur which is placed outside both Stenopterygiidae and Ophthalmosauridae
. Both Maisch (2008) and Caine and Benton (2011) performed cladistic analyses that found Hauffiopteryx to be either a basalmost
member of Eurhinosauria or a basalmost member of Thunnosauria (which is an equivalent position to a basalmost member of Stenopterygiidae sensu Maisch [2008] with exclusion of Ichthyosaurus). These results mean that Stenopterygiidae is a monotypic family which include only the type genus Stenopterygius.
, I. quadriscissus. Otto Jaekel
in 1904
reassigned it to its own genus, Stenopterygius. The type species
is therefore Stenopterygius quadriscissus. The generic name is derived from stenos, Greek
for "narrow", and pteryx (πτερυξ), Greek for "fin" or "wing".
Stenopterygius was physically similar to the better known Ichthyosaurus
, but had a smaller skull
and narrower flippers. Beautifully preserved fossil
s of Stenopterygius have been found in Germany
. Its skull was extended into a kind of a beak and was armed with a quantity of large teeth. The limbs had been transformed to fin-like structures. The tail terminated in a large, semicircular, leathery, vertical caudal fin and even a triangular dorsal fin
was present.
The habits of Stenopterygius were similar to those of present-day dolphins. It spent most of its life in the open sea, where it hunted fish, cephalopod
s and other animals. The abdominal cavity of skeletons of this ichthyosaur often contains the remains of such food.
One famous fossil is that of a mother and baby that died in childbirth
(ichthyosaurs were viviparous). This proved that ichthyosaur infants were born tail-first, just like cetacea
ns, to prevent them from drowning before fully clearing the birth canal.
Stenopterygius was a very fast swimmer, with a cruising speed similar to that of tuna
, which is among the fastest of all living fishes.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of thunnosaur ichthyosaur
Ichthyosaur
Ichthyosaurs were giant marine reptiles that resembled fish and dolphins...
known from 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...
(England
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...
, France
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
, 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...
, Luxembourg
Luxembourg
Luxembourg , officially the Grand Duchy of Luxembourg , is a landlocked country in western Europe, bordered by Belgium, France, and Germany. It has two principal regions: the Oesling in the North as part of the Ardennes massif, and the Gutland in the south...
and Switzerland
Switzerland
Switzerland name of one of the Swiss cantons. ; ; ; or ), in its full name the Swiss Confederation , is a federal republic consisting of 26 cantons, with Bern as the seat of the federal authorities. The country is situated in Western Europe,Or Central Europe depending on the definition....
). Maximum length was 4 meters.
Description
Ichthyosaurus
Ichthyosaurus is an extinct genus of ichthyosaur from the Early Jurassic of Europe . It is among the best known ichthyosaur genera, with the Order Ichthyosauria being named after it...
triscissus to be a valid species of Stenopterygius. The type specimens of S. longifrons, S. megacephalus, and S. megalorhinus were all referred to this species as the name I. triscissus has a priority over them. Some specimens previously referred to S. megalorhinus, as well as the holotype of S. cuneiceps, were found to belong to a species of their own for which the binomen Stenopterygius uniter can be used.
As the holotype of S. uniter was destroyed in World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
, Maisch proposed a neotype. Maisch also found that S. promegacephalus is a nomen dubium
Nomen dubium
In zoological nomenclature, a nomen dubium is a scientific name that is of unknown or doubtful application...
as it is based on juvenile specimen, and that the lectotype of S. hauffianus can be determined as Stenopterygius cf. S. quadriscissus at best, and therefore this species should be considered a nomen dubium
Nomen dubium
In zoological nomenclature, a nomen dubium is a scientific name that is of unknown or doubtful application...
. He found out that most specimens previously referred to S. hauffianus can be referred to S. quadriscissus, while the rest belongs to a highly distinctive new taxon that can't be referred to any valid species of Stenopterygius. This species was reassigned to its own genus, Hauffiopteryx
Hauffiopteryx
Hauffiopteryx is an extinct genus of ichthyosaur known from Germany, Luxembourg and Somerset of the United Kingdom.-Description:Hauffiopteryx was first described by Michael W. Maisch on the basis of some specimens that previously referred to Stenopterygius hauffianus. Maisch found that the...
.
Lectotype
In botanical nomenclature and zoological nomenclature, a lectotype is a kind of name-bearing type. When a species was originally described on the basis of a name-bearing type consisting of multiple specimens, one of those may be designated as the lectotype...
GPIT 43/0219-1, articulate
Articulate
Articulate may refer to:*Articulate *Articulate sign*Articulate sound*Joint, also known as articulation*Word modified by an article...
d complete skeleton
Skeleton
The skeleton is the body part that forms the supporting structure of an organism. There are two different skeletal types: the exoskeleton, which is the stable outer shell of an organism, and the endoskeleton, which forms the support structure inside the body.In a figurative sense, skeleton can...
which preserved a very large embryo. The animal is about 3.15 m (10.3 ft) in length. It was collected from the Harpoceras elegantulum-exaratum ammonoid subzones (more specifically Lias ε II3-4), Harpoceras falcifer zone, of the famous Posidonien-Schiefer lagerstätte
Lagerstätte
A Lagerstätte is a sedimentary deposit that exhibits extraordinary fossil richness or completeness.Palaeontologists distinguish two kinds....
(Posidonia Shale
Posidonia Shale
The Posidonia Shale is a Lower Jurassic geological formation famous for its exceptionally well-preserved complete skeletons of fossil marine fish and reptiles. The Posidonienschiefer as German paleontologists call it, takes its name from the ubiquitous fossils of Posidonia bronni that characterize...
) of Holzmaden
Holzmaden
Holzmaden is a town in Baden-Württemberg, Germany that lies between Stuttgart and Ulm.The ground in and around the city contains rich layers of well preserved fossils of the Jurassic period. The fossils are found in the 160 million year old Posidonia Shale and displayed in the local Museum Hauff...
, dating to the early Toarcian
Toarcian
The Toarcian is, in the ICS' geologic timescale, an age or stage in the Early or Lower Jurassic. It spans the time between 183.0 Ma and 175.6 Ma...
stage of the Early Jurassic
Early Jurassic
The Early Jurassic epoch is the earliest of three epochs of the Jurassic period...
, about 182 million years ago. Maisch referred to the type species 30 additional specimens, all came from Dobbertin of Mecklenburg-Vorpommern and Holzmaden
Holzmaden
Holzmaden is a town in Baden-Württemberg, Germany that lies between Stuttgart and Ulm.The ground in and around the city contains rich layers of well preserved fossils of the Jurassic period. The fossils are found in the 160 million year old Posidonia Shale and displayed in the local Museum Hauff...
, Germany and Dudelange
Dudelange
Dudelange is a commune with city status in southern Luxembourg. It is the fourth-most populous commune, with over 18,300 inhabitants. Dudelange is situated close to the border to France....
, Luxembourg. They were collected from the Harpoceras palum to H. falciferum ammonoid subzones (Lias ε I2-II11, lower-middle early Toarcian), Harpoceras tenuicostatum-falcifer zones, of the Posidonia Shale. S. triscissus is known from 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...
GPIT 12/0224-2, articulate
Articulate
Articulate may refer to:*Articulate *Articulate sign*Articulate sound*Joint, also known as articulation*Word modified by an article...
d almost complete skeleton
Skeleton
The skeleton is the body part that forms the supporting structure of an organism. There are two different skeletal types: the exoskeleton, which is the stable outer shell of an organism, and the endoskeleton, which forms the support structure inside the body.In a figurative sense, skeleton can...
. The animal is a young adult about 2.1 m (6.9 ft) in length. It was collected from the Harpoceras exaratum-elegans ammonoid subzones (more specifically Lias ε II6), Harpoceras falcifer zone, of the Posidonia Shale
Posidonia Shale
The Posidonia Shale is a Lower Jurassic geological formation famous for its exceptionally well-preserved complete skeletons of fossil marine fish and reptiles. The Posidonienschiefer as German paleontologists call it, takes its name from the ubiquitous fossils of Posidonia bronni that characterize...
, in Ohmden
Ohmden
Ohmden is a town in the district of Esslingen in Baden-Württemberg in Germany....
, dating to the middle Early Toarcian
Toarcian
The Toarcian is, in the ICS' geologic timescale, an age or stage in the Early or Lower Jurassic. It spans the time between 183.0 Ma and 175.6 Ma...
stage of the Early Jurassic
Early Jurassic
The Early Jurassic epoch is the earliest of three epochs of the Jurassic period...
. Maisch referred to this species 13 additional specimens, all came from various localities in England, France, Germany, Luxembourg and Switzerland. They were collected from the Lias ε II1-III, dating to the middle-late Early Toarcian. S. uniter is known from 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 14216, articulated complete skeleton which was destroyed in World War II. The animal is an adult about 3.35 m (11 ft) in length. The proposed neotype is GPIT 1491/10, articulated almost complete skeleton. The animal is a young adult about 2.34 m (7.7 ft) in length. It was collected from the Harpoceras falcifer ammonoid subzones (more specifically Lias ε II10), Harpoceras falcifer zone, of the Posidonia Shale
Posidonia Shale
The Posidonia Shale is a Lower Jurassic geological formation famous for its exceptionally well-preserved complete skeletons of fossil marine fish and reptiles. The Posidonienschiefer as German paleontologists call it, takes its name from the ubiquitous fossils of Posidonia bronni that characterize...
, in Holzmaden
Holzmaden
Holzmaden is a town in Baden-Württemberg, Germany that lies between Stuttgart and Ulm.The ground in and around the city contains rich layers of well preserved fossils of the Jurassic period. The fossils are found in the 160 million year old Posidonia Shale and displayed in the local Museum Hauff...
, dating to the middle Early Toarcian
Toarcian
The Toarcian is, in the ICS' geologic timescale, an age or stage in the Early or Lower Jurassic. It spans the time between 183.0 Ma and 175.6 Ma...
stage of the Early Jurassic
Early Jurassic
The Early Jurassic epoch is the earliest of three epochs of the Jurassic period...
. Maisch referred to this species 10 additional specimens, all came from Holzmaden. They were collected from the Harpoceras exaratum to H. falciferum ammonoid subzones (Lias ε II6-II11, middle early Toarcian), Harpoceras falcifer zones, of the Posidonia Shale.
Additional materials were described by Hannah Caine and Michael J. 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....
in 2011, from the early Toarcian of Strawberry Bank, Ilminster
Ilminster
Ilminster is a country town and civil parish in the countryside of south west Somerset, England, with a population of 4,781. Bypassed a few years ago, the town now lies just east of the intersection of the A303 and the A358...
of England. The specimens are all juveniles or infants which preserved mostly by almost complete skeletons and some skulls. They include BRLSI
Bath Royal Literary and Scientific Institution
The Bath Royal Literary and Scientific Institution is an educational charity based in Bath, England. It was founded in 1824 and provides a museum, an independent library, exhibition space, meeting rooms and a programme of public lectures, discussion groups and exhibitions related to science, the...
M1405, BRLSI M1407, BRLSI M1408, BRLSI M1409. Caine and Benton referred these specimens to S. triscissus.
Maisch and Matzke (2000) and Maisch (2010) regarded Chacaicosaurus
Chacaicosaurus
Chacaicosaurus is an extinct genus of long-snouted thunnosaur ichthyosaur known from northwestern Patagonia of Argentina.-Description:Chacaicosaurus is known only from the holotype MOZ 5803, articulated partial skeleton which preserved partial skull and almost complete forefin...
and Hauffiopteryx
Hauffiopteryx
Hauffiopteryx is an extinct genus of ichthyosaur known from Germany, Luxembourg and Somerset of the United Kingdom.-Description:Hauffiopteryx was first described by Michael W. Maisch on the basis of some specimens that previously referred to Stenopterygius hauffianus. Maisch found that the...
to be stenopterygiids. However, they didn't performed any cladistic analyses to confirm these claims. Fischer et al. (2011) performed a cladistic analysis that found Chacaicosaurus to be a basal
Basal (phylogenetics)
In phylogenetics, a basal clade is the earliest clade to branch in a larger clade; it appears at the base of a cladogram.A basal group forms an outgroup to the rest of the clade, such as in the following example:...
thunnosaur which is placed outside both Stenopterygiidae and Ophthalmosauridae
Ophthalmosauridae
Ophthalmosauridae is an extinct family of thunnosaur ichthyosaurs from the Middle Jurassic to the early Late Cretaceous of Asia, Australia, Europe, North America and South America. Currently, the oldest known ophthalmosaurid is Mollesaurus from the early Bajocian of Argentina. Named by George H...
. Both Maisch (2008) and Caine and Benton (2011) performed cladistic analyses that found Hauffiopteryx to be either a basalmost
Basal (phylogenetics)
In phylogenetics, a basal clade is the earliest clade to branch in a larger clade; it appears at the base of a cladogram.A basal group forms an outgroup to the rest of the clade, such as in the following example:...
member of Eurhinosauria or a basalmost member of Thunnosauria (which is an equivalent position to a basalmost member of Stenopterygiidae sensu Maisch [2008] with exclusion of Ichthyosaurus). These results mean that Stenopterygiidae is a monotypic family which include only the type genus Stenopterygius.
Etymology
Stenopterygius was originally named by Quenstedt in 1856 as a species of IchthyosaurusIchthyosaurus
Ichthyosaurus is an extinct genus of ichthyosaur from the Early Jurassic of Europe . It is among the best known ichthyosaur genera, with the Order Ichthyosauria being named after it...
, I. quadriscissus. Otto Jaekel
Otto Jaekel
Otto Max Johannes Jaekel was a German paleontologist and geologist.Jaekel was born in Neusalz , Prussian Silesia. He studied geology and paleontology in Liegnitz . After graduating in 1883, he moved to Breslau and studied under Ferdinand Roemer until 1885. Karl von Zittel awarded a PhD to Jaekel...
in 1904
1904 in paleontology
-Newly named dinosaurs:Data courtesy of George Olshevsky's dinosaur genera list and Dr. Jeremy Montague's dinosaur genus database.-Non-mammalian:-References:* Brown, B. Stomach stones and food of plesiosaurs, Science, n.s. 20, : 184-185...
reassigned it to its own genus, Stenopterygius. The type species
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
is therefore Stenopterygius quadriscissus. The generic name is derived from stenos, 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;...
for "narrow", and pteryx (πτερυξ), Greek for "fin" or "wing".
Palaeobiology
Ichthyosaurus
Ichthyosaurus is an extinct genus of ichthyosaur from the Early Jurassic of Europe . It is among the best known ichthyosaur genera, with the Order Ichthyosauria being named after it...
, but had a smaller skull
Skull
The skull is a bony structure in the head of many animals that supports the structures of the face and forms a cavity for the brain.The skull is composed of two parts: the cranium and the mandible. A skull without a mandible is only a cranium. Animals that have skulls are called craniates...
and narrower flippers. Beautifully preserved fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
s of Stenopterygius have been found in 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...
. Its skull was extended into a kind of a beak and was armed with a quantity of large teeth. The limbs had been transformed to fin-like structures. The tail terminated in a large, semicircular, leathery, vertical caudal fin and even a triangular dorsal fin
Dorsal fin
A dorsal fin is a fin located on the backs of various unrelated marine and freshwater vertebrates, including most fishes, marine mammals , and the ichthyosaurs...
was present.
The habits of Stenopterygius were similar to those of present-day dolphins. It spent most of its life in the open sea, where it hunted fish, cephalopod
Cephalopod
A cephalopod is any member of the molluscan class Cephalopoda . These exclusively marine animals are characterized by bilateral body symmetry, a prominent head, and a set of arms or tentacles modified from the primitive molluscan foot...
s and other animals. The abdominal cavity of skeletons of this ichthyosaur often contains the remains of such food.
One famous fossil is that of a mother and baby that died in childbirth
Childbirth
Childbirth is the culmination of a human pregnancy or gestation period with the birth of one or more newborn infants from a woman's uterus...
(ichthyosaurs were viviparous). This proved that ichthyosaur infants were born tail-first, just like cetacea
Cetacea
The order Cetacea includes the marine mammals commonly known as whales, dolphins, and porpoises. Cetus is Latin and is used in biological names to mean "whale"; its original meaning, "large sea animal", was more general. It comes from Ancient Greek , meaning "whale" or "any huge fish or sea...
ns, to prevent them from drowning before fully clearing the birth canal.
Stenopterygius was a very fast swimmer, with a cruising speed similar to that of tuna
Tuna
Tuna is a salt water fish from the family Scombridae, mostly in the genus Thunnus. Tuna are fast swimmers, and some species are capable of speeds of . Unlike most fish, which have white flesh, the muscle tissue of tuna ranges from pink to dark red. The red coloration derives from myoglobin, an...
, which is among the fastest of all living fishes.