Belemnotheutis
Encyclopedia
Belemnotheutis is an extinct
genus
of cephalopod
s which existed from the Middle
to Upper Jurassic (164.7 to 150.8 million years ago). They are related to belemnites
but differ significantly in morphology
. Belemnotheutis fossil
s are some of the best preserved among coleoids. Remains of soft tissue are well-documented in some specimens, even down to microscopic muscle tissue. In 2008, a group of paleontologists recovered ink chambers
of several specimens that still contained viable ink.
This genus was also the subject of a dispute between several eminent 19th century British paleontologists, notably between Richard Owen
and Gideon Mantell
.
soft tissue. The mantle
, fins, head, arms
, and hooks are well-documented from remains preserved in Lagerstätte
n. One specimen recovered from Christian Malford
, Wiltshire
and currently displayed in the Paleontology Department of the Natural History Museum
in London is fossilized clasping a fish.
Belemnotheutis is not a 'true' belemnite (suborder Belemnitina
) but a closely related coleoid. Both belemnotheutids and belemnites resembled modern squid
s except that they had chambered internal skeleton
s called phragmocone
s.
The apical portion of the Belemnotheutis internal skeleton is called the rostrum (plural: rostra) or the guard. The rostrum of Belemnotheutis differs significantly from that of true belemnites. Unlike the bullet-shaped dense guards of belemnites, the rostrum of Belemnotheutis is only present as a very thin sheath. It was also composed of aragonite
rather than the heavy calcite
of belemnites. In large specimens the rostrum can reach a maximum of only 1 mm (0.0393700787401575 in) in thickness near the tip. The outer surface was covered by a thin organic layer in the live animal. In true belemnites, the large dense rostra acted as a counterbalance, keeping the animal horizontally oriented when swimming. It was long assumed that Belemnotheutis were confined to shallow waters, unable to venture into deeper waters due to the absence of the heavy rostra. The discovery of cameral desposits in the phragmocones of Belemnotheutis in 1952 made it clear that they were capable of controlling buoyancy.
The phragmocone of Belemnotheutis is short and blunt, measuring around 35 mm (1.4 in) to 86 mm (3.4 in) in length. The outer wall of the phragmocone is called the conotheca, distinct from the rostrum. It begins approximately 50 mm (2 in) from the tip of the phragmocone and consists of a nacre
ous outer layer and an inner lamellar layer. The outer layer gradually thins from 0.6 mm (0.0236220472440945 in) in thickness to only about 0.1 mm (0.00393700787401575 in) thick at about 65 mm (2.6 in) further down the shell until it eventually disappears around the opening of the phragmocone (the peristome
). Sometimes there is a hollow gap between the rostrum and the lamellar layer of the conotheca, indicating either organic content that have since disappeared or disintegration of the lamellar layer itself. The phragmocone
of Belemnotheutis had about 50 chambers that were originally aragonitic
, though they are usually replaced by calcium phosphate
during the process of fossilization.
At the very tip of the phragmocone beneath the rostrum is an embryonic shell known as the protoconch
. In Belemnotheutis, like in other belemnotheutids, the protoconch is roughly cup-shaped and sealed. This was thought to be another method of distinguishing it from other belemnites which usually have ball-shaped protoconchs. However, it is probably a taphonomic artefact, with the protoconch being spherical like other belemnites.
The long, weakly tapering structure in the dorsal anterior part of the internal skeleton is called the proostracum. It is striated longitudinally and often shows minute holes left by boring organisms usually less than 1 μm in diameter. The length of the proostracum is one to two times the length of the phragmocone. The proostracum was a thin, delicate structure substantially narrower than the phragmocone. Its original composition is unknown and it is always found separated from the phragmocone and the rostrum and often crushed. Whether the proostracum was connected to or derived from the phragmocone is still a subject of debate among paleontologists. Its general morphology, however, resembles that of true belemnites rather than those from other 'unusual' belemnoid coeloids with short rostra like Permoteuthis
and Phragmoteuthis
.
The head is not well preserved in known specimens. It comprised approximately 20% of the body length (excluding the arms). Brain cartilage is observed in some specimens, as well as a pair of aragonitic statoliths
which helped the animal determine horizontal orientation when swimming. Belemnotheutis, like most of the other belemnoids, had ten arms of equal length lined with two rows of inward-pointing hooks each. Each of the hooks were composed of several sections. The curved pointed tip is called the uncinus and was probably the only part of the hooks exposed. The rest of the hook (the shaft and the base) were embedded in a sheath of soft tissue below the orbicular scar, a small groove where the tissue attachment terminated. They are also believed to have been stalked and mobile, helping the animal manipulate its prey. Traces of functional suckers have been found and these constitute a single row on each arm, alternating in between the pairs of hooks. The size of the suckers decreases distally along the arms, with the largest (around 2 mm (0.078740157480315 in) in diameter) being closest to the head. The length of the arms varies with the size of the individual but may have reached 100 mm (3.9 in) in larger specimens.
Belemnotheutis had a cylindriconical muscular
mantle
covered by an outer and inner skin (tunic). Traces of a criss-cross pattern composed of collagen
fibers have been observed in the surface of some well-preserved fossils. The cross section of the exceptionally preserved body wall of a specimen from the Oxford Clay
formations also reveals alternating bands of concentrically and radially oriented body fibers. They imply that Belemnotheutis were powerful swimmers and agile predators, similar to modern shallow-water squid species. The animal reached 10 to 30 cm (3.9 to 11.8 in) in length, including its arms. The body diameter was around 12 to 14% of the mantle length. At the center of the dorsal surface of the rostrum is a narrow V-shaped groove running about 3/5ths the length of the phragmocone from the apex, with two rounded ridges at its left and right sides. These grooves are one of the most distinctive features of the Belemnotheutidae and are theorized to have served as attachments to terminal oval or oar-shaped fins like in some modern squids. The siphuncle
is marginal and located ventrally. Directly in front of the phragmocone was an ink sac
that could reach 25 mm (0.984251968503937 in) long in large specimens. Intestinal casts (cololites) as well as the orientations and positions of fossilized remains reveal that the animal preyed on fish and other coleoids in life. Their great abundance in certain formations indicate that Belemnotheutis were highly gregarious animals, congregating in large monospecific or polyspecific shoals.
of belemnites were first discovered by the famous British
fossil collector
and paleontologist Mary Anning
in 1826. She and her friend Elizabeth Philpot
, another fossil collector, along with her brother Joseph Anning, succeeded in revivifying the ink and used it to illustrate ichthyosaur
and pterosaur
fossils. The ink recovered from such fossils were also used to draw fossil ichthyosaurs by Sir Henry Thomas De la Beche
, a friend and supporter of Mary Anning.
In 2008, an excavation team led by the British Geological Survey
in Christian Malford
recovered fossilized ink sacs from several remarkably preserved remains of Belemnotheutis antiquus in the Oxford Clay Formation. The specimens were fossilized rapidly in apatite
(calcium phosphate) through a process paleontologist Dr. Phil Wilby called "The Medusa Effect". By mixing it with ammonia
solution, the team was able to return the ink to its liquid form. Bringing to mind the 19th century practices of the aforementioned early paleontologists, they used the ~150 million year old ink to draw a replica of the original illustration of Belemnotheutis as drawn by Joseph Channing Pearce. Dr. Wilby called the drawing "the ultimate self-portrait".
, South West England
, two years after excavations from the construction of the Great Western Railway
uncovered parts of the Oxford Clay formation. It is unknown why he chose the spelling Belemnotheutis rather than what common convention would have dictated - Belemnoteuthis. He described his discovery to the Geological Society of London
in the same year.
In 1843, Richard Owen
acquired specimens of Belemnotheutis from the same locality from another paleontologist, Samuel Peace Pratt. He formally published a paper on 1844 (On the Belemnites, Philosophical Transactions of the Royal Society
), naming the specimens Belemnites owenii Pratt, after himself and crediting Pratt with the discovery while failing to mention Pearce. He believed that the specimens were of the genus Belemnites whose typically lengthy rostra simply got separated. He sent a copy of the paper to Pearce in the same year, proving that he was actually aware of Pearce's earlier description but had deliberately omitted any mention of him. Pearce responded by stating that examination by another paleontologist James Scott Bowerbank
, supported his belief that fossils did not possess the bullet-shaped guards typical of Belemnites but instead had rostra in the form of very thin sheaths. Bowerbanks confirmed this assertion but supported Owen's assignment of Belemnites, saying that the presence of very short rostra did not justify the classification of Belemnotheutis as a separate genus from Belemnites.
Owen received a Royal Medal
from the Royal Society
in 1846 for the 1844 paper, further inducing Pearce to protest what he viewed as erroneous descriptions of the specimens. In 1847, the London Geological Journal published a paper by Pearce of his objections to Owen's paper. At the same time the editor of the paper and another paleontologist, Edward Charlesworth, published an editorial criticizing Owen for deliberately failing to credit Pearce with the discovery of Belemnotheutis, as well as his apparent disregard to the opinions of less well-known paleontologists like Pearce. This was also the first time that Pearce described the specific epithet antiquus to the fossils. Pearce died later in the same year in May 1847 taking no further part in what was to become a controversy. Shortly after his death, the same paper published the support of William Cunnington
, a fossil collector
, for this description as opposed to Owen's conclusions.
In 1848, Gideon Mantell
read a description of Belemnotheutis specimens recovered by his son Reginald Neville Mantell to the Royal Society. His descriptions supported that of Pearce's views and held that the differences between belemnites and Belemnotheutis were enough to justify it being a separate genus. He also described the characteristic groove on the apical dorsal surface of the Belemnotheutis for the first time (structures which Owen had attributed as artifacts of crushing). He had expected Owen, who was present during the session, to support this amendment. Instead, Owen ridiculed Mantell, further aggravating the famous feud between the two.
Mantell continued to assert his position until his death in 1852, gaining supporters in other eminent paleontologists like Edward Forbes
and Charles Lyell
against Owen with regards to the true morphology of Belemnotheutis. By then the hostility between Owen and Mantell had escalated, Owen going so far as to oppose the awarding of the Royal Medal to Mantell for his work in 1849. Mantell did eventually receive the Royal Medal for his work on Iguanodon
to which Owen had attempted to claim another authority much in the same way that he had named Belemnotheutis after himself.
In 1860, three years after Mantell's death, Owen eventually published an amendment to his earlier descriptions. He acknowledged that Belemnotheutis indeed had very thin rostra and was distinct from the genus Belemnites. He did so only after other prominent authorities described the very similar Acanthoteuthis
and were considering Belemnotheutis as its synonym. However, he never recanted his earlier criticism of both Pearce and Mantell.
to the Upper Jurassic epoch
, from the Callovian
age (164.7 to 161.2 mya) to the Kimmeridgian
age (155.7 to 150.8 mya). The belemnotheutid Acanthoteuthis
, a close relative which is treated by some paleontologists as synonymous with Belemnotheutis, is known to have existed from as early as the Callovian
age (164.7 to 161.2 mya) of the Middle Jurassic
epoch to as late as the Aptian
age (125 to 112 mya) of the Lower Cretaceous epoch. The earliest known possible remains of belemnotheutids (genera Chitinobelus and Chondroteuthis
) come from the Lower Jurassic, from phragmocones and rostra recovered from Toarcian
formations in Dumbleton
, Gloucestershire
, and Ilminster
, Somerset
, England
. However, these remains seem to have possessed the typical calcitic
rostra of true belemnites rather than the characteristic aragonitic rostra of belemnotheutids.
Belemnotheutis serve as index fossil
s. They are mostly found in Jurassic
formations like the Kimmeridge Clay
formation, the Oxford Clay
formation, and the Solnhofen Limestone
formation. Their geographic range, thus far, is confined to Europe
.
Belemnotheutidae. Belemnotheutis and other belemnotheutids are considered by some paleontologists to be distinct from true belemnites (suborder Belemnitina
). Most authorities like Jeletzky (1966), Bandel and Kulicki (1988), and Peter Doyle (1990) classify it under Belemnitida in the suborder Belemnotheutina (the classification used by this article). Others like Donovan (1977) and Engeser and Reitner (1981) classify it as a distinct order, Belemnotheutida, based on the aragonitic constitution of the rostra, the shape of the proostraca, protoconchs, and the arm crowns, among other morphological factors.
Belemnotheutis has been continually spelled as Belemnoteuthis by authors who believed that Pearce had made an honest mistake in naming the specimens. In 1999, D.T. Donovan and M.D. Crane succeeded in convincing the International Commission on Zoological Nomenclature
that the spelling was intentional, citing historical usage of the spelling Greek θευτίς (theutis) as a valid variant of the usual τευθίς (teuthis, 'squid'). Subsequently, the accepted spelling
is now formally Belemnotheutis.
Belemnotheutis montefiorei has been transferred to the genus Phragmoteuthis
and B. rosenkrantzi to the genus Groenlandibelus.
Extinction
In biology and ecology, extinction is the end of an organism or of a group of organisms , normally a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point...
genus
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 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 which existed from the Middle
Middle Jurassic
The Middle Jurassic is the second epoch of the Jurassic Period. It lasted from 176-161 million years ago. In European lithostratigraphy, rocks of this Middle Jurassic age are called the Dogger....
to Upper Jurassic (164.7 to 150.8 million years ago). They are related to belemnites
Belemnitina
Belemnitina is a genus of belemnite, an extinct group of cephalopods....
but differ significantly in morphology
Morphology (biology)
In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....
. Belemnotheutis fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
s are some of the best preserved among coleoids. Remains of soft tissue are well-documented in some specimens, even down to microscopic muscle tissue. In 2008, a group of paleontologists recovered ink chambers
Cephalopod ink
Cephalopod ink is a dark pigment released into water by most species of cephalopod, usually as an escape mechanism. All cephalopods, with the exception of the Nautilidae and the species of octopus belonging to the suborder Cirrina, are able to release ink....
of several specimens that still contained viable ink.
This genus was also the subject of a dispute between several eminent 19th century British paleontologists, notably between Richard Owen
Richard Owen
Sir Richard Owen, FRS KCB was an English biologist, comparative anatomist and palaeontologist.Owen is probably best remembered today for coining the word Dinosauria and for his outspoken opposition to Charles Darwin's theory of evolution by natural selection...
and Gideon Mantell
Gideon Mantell
Gideon Algernon Mantell MRCS FRS was an English obstetrician, geologist and palaeontologist...
.
Description
Belemnotheutis fossils are sometimes found in remarkable states of preservation, some specimens retaining permineralizedPermineralization
Permineralization is a process of fossilization in which mineral deposits form internal casts of organisms. Carried by water, these minerals fill the spaces within organic tissue...
soft tissue. The mantle
Mantle (mollusc)
The mantle is a significant part of the anatomy of molluscs: it is the dorsal body wall which covers the visceral mass and usually protrudes in the form of flaps well beyond the visceral mass itself.In many, but by no means all, species of molluscs, the epidermis of the mantle secretes...
, fins, head, arms
Cephalopod arm
A cephalopod arm is distinct from a tentacle, though the terms are often used interchangeably.Generally, cephalopod arms have suckers along most of their length, as opposed to tentacles, which have suckers only near their ends. Octopuses have eight arms and no tentacles, while squid and cuttlefish...
, and hooks are well-documented from remains preserved in Lagerstätte
Lagerstätte
A Lagerstätte is a sedimentary deposit that exhibits extraordinary fossil richness or completeness.Palaeontologists distinguish two kinds....
n. One specimen recovered from Christian Malford
Christian Malford
Christian Malford is a small village in the county of Wiltshire in England. The unusual name is evidently a corruption of Christ mal Ford, Old English moel, mal being a mark: "Christ’s mal" is Christ’s mark or sign, the cross. The name signified "Cross Ford". Deeds from Glastonbury Abbey cartulary...
, Wiltshire
Wiltshire
Wiltshire is a ceremonial county in South West England. It is landlocked and borders the counties of Dorset, Somerset, Hampshire, Gloucestershire, Oxfordshire and Berkshire. It contains the unitary authority of Swindon and covers...
and currently displayed in the Paleontology Department of the Natural History Museum
Natural History Museum
The Natural History Museum is one of three large museums on Exhibition Road, South Kensington, London, England . Its main frontage is on Cromwell Road...
in London is fossilized clasping a fish.
Belemnotheutis is not a 'true' belemnite (suborder Belemnitina
Belemnitina
Belemnitina is a genus of belemnite, an extinct group of cephalopods....
) but a closely related coleoid. Both belemnotheutids and belemnites resembled modern squid
Squid
Squid are cephalopods of the order Teuthida, which comprises around 300 species. Like all other cephalopods, squid have a distinct head, bilateral symmetry, a mantle, and arms. Squid, like cuttlefish, have eight arms arranged in pairs and two, usually longer, tentacles...
s except that they had chambered internal skeleton
Endoskeleton
An endoskeleton is an internal support structure of an animal, composed of mineralized tissue. Endoskeleton develops within the skin or in the deeper body tissues. The vertebrate is basically an endoskeleton made up of two types of tissues . During early embryonic development the endoskeleton is...
s called phragmocone
Phragmocone
The phragmocone is the chambered portion of the shell of a cephalopod. It is divided by septa into camerae.In most nautiloids and ammonoids, the phragmocone is a long, straight, curved, or coiled structure, in which the camarae are linked by a siphuncle which determines buoyancy by means of gas...
s.
The apical portion of the Belemnotheutis internal skeleton is called the rostrum (plural: rostra) or the guard. The rostrum of Belemnotheutis differs significantly from that of true belemnites. Unlike the bullet-shaped dense guards of belemnites, the rostrum of Belemnotheutis is only present as a very thin sheath. It was also composed of aragonite
Aragonite
Aragonite is a carbonate mineral, one of the two common, naturally occurring, crystal forms of calcium carbonate, CaCO3...
rather than the heavy calcite
Calcite
Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate . The other polymorphs are the minerals aragonite and vaterite. Aragonite will change to calcite at 380-470°C, and vaterite is even less stable.-Properties:...
of belemnites. In large specimens the rostrum can reach a maximum of only 1 mm (0.0393700787401575 in) in thickness near the tip. The outer surface was covered by a thin organic layer in the live animal. In true belemnites, the large dense rostra acted as a counterbalance, keeping the animal horizontally oriented when swimming. It was long assumed that Belemnotheutis were confined to shallow waters, unable to venture into deeper waters due to the absence of the heavy rostra. The discovery of cameral desposits in the phragmocones of Belemnotheutis in 1952 made it clear that they were capable of controlling buoyancy.
The phragmocone of Belemnotheutis is short and blunt, measuring around 35 mm (1.4 in) to 86 mm (3.4 in) in length. The outer wall of the phragmocone is called the conotheca, distinct from the rostrum. It begins approximately 50 mm (2 in) from the tip of the phragmocone and consists of a nacre
Nacre
Nacre , also known as mother of pearl, is an organic-inorganic composite material produced by some mollusks as an inner shell layer; it is also what makes up pearls. It is very strong, resilient, and iridescent....
ous outer layer and an inner lamellar layer. The outer layer gradually thins from 0.6 mm (0.0236220472440945 in) in thickness to only about 0.1 mm (0.00393700787401575 in) thick at about 65 mm (2.6 in) further down the shell until it eventually disappears around the opening of the phragmocone (the peristome
Peristome
The word peristome is derived from the Greek peri, meaning 'around' or 'about', and stoma, 'mouth'. It is a term used to describe various anatomical features that surround an opening to an organ or structure. The term is used in plants and invertebrate animals, such as in describing the shells of...
). Sometimes there is a hollow gap between the rostrum and the lamellar layer of the conotheca, indicating either organic content that have since disappeared or disintegration of the lamellar layer itself. The phragmocone
Phragmocone
The phragmocone is the chambered portion of the shell of a cephalopod. It is divided by septa into camerae.In most nautiloids and ammonoids, the phragmocone is a long, straight, curved, or coiled structure, in which the camarae are linked by a siphuncle which determines buoyancy by means of gas...
of Belemnotheutis had about 50 chambers that were originally aragonitic
Aragonite
Aragonite is a carbonate mineral, one of the two common, naturally occurring, crystal forms of calcium carbonate, CaCO3...
, though they are usually replaced by calcium phosphate
Calcium phosphate
Calcium phosphate is the name given to a family of minerals containing calcium ions together with orthophosphates , metaphosphates or pyrophosphates and occasionally hydrogen or hydroxide ions ....
during the process of fossilization.
At the very tip of the phragmocone beneath the rostrum is an embryonic shell known as the protoconch
Protoconch
A protoconch is an embryonic or larval shell of some classes of molluscs, e.g., the initial chamber of an ammonite or the larval shell of a gastropod...
. In Belemnotheutis, like in other belemnotheutids, the protoconch is roughly cup-shaped and sealed. This was thought to be another method of distinguishing it from other belemnites which usually have ball-shaped protoconchs. However, it is probably a taphonomic artefact, with the protoconch being spherical like other belemnites.
The long, weakly tapering structure in the dorsal anterior part of the internal skeleton is called the proostracum. It is striated longitudinally and often shows minute holes left by boring organisms usually less than 1 μm in diameter. The length of the proostracum is one to two times the length of the phragmocone. The proostracum was a thin, delicate structure substantially narrower than the phragmocone. Its original composition is unknown and it is always found separated from the phragmocone and the rostrum and often crushed. Whether the proostracum was connected to or derived from the phragmocone is still a subject of debate among paleontologists. Its general morphology, however, resembles that of true belemnites rather than those from other 'unusual' belemnoid coeloids with short rostra like Permoteuthis
Permoteuthis
Permoteuthis is a genus of belemnite, an extinct group of cephalopods....
and Phragmoteuthis
Phragmoteuthis
Phragmoteuthis is a genus of coleoid cephalopod known from the late Triassic to the lower Jurassic. Its soft tissue has been preserved; some specimens contain intact ink sacs, and others, gills. It had an internal phragmocone and ten arms....
.
The head is not well preserved in known specimens. It comprised approximately 20% of the body length (excluding the arms). Brain cartilage is observed in some specimens, as well as a pair of aragonitic statoliths
Statocyst
The statocyst is a balance sensory receptor present in some aquatic invertebrates, including bivalves, cnidarians, echinoderms, cephalopods, and crustaceans. A similar structure is also found in Xenoturbella. The statocyst consists of a sac-like structure containing a mineralised mass and numerous...
which helped the animal determine horizontal orientation when swimming. Belemnotheutis, like most of the other belemnoids, had ten arms of equal length lined with two rows of inward-pointing hooks each. Each of the hooks were composed of several sections. The curved pointed tip is called the uncinus and was probably the only part of the hooks exposed. The rest of the hook (the shaft and the base) were embedded in a sheath of soft tissue below the orbicular scar, a small groove where the tissue attachment terminated. They are also believed to have been stalked and mobile, helping the animal manipulate its prey. Traces of functional suckers have been found and these constitute a single row on each arm, alternating in between the pairs of hooks. The size of the suckers decreases distally along the arms, with the largest (around 2 mm (0.078740157480315 in) in diameter) being closest to the head. The length of the arms varies with the size of the individual but may have reached 100 mm (3.9 in) in larger specimens.
Belemnotheutis had a cylindriconical muscular
Muscle
Muscle is a contractile tissue of animals and is derived from the mesodermal layer of embryonic germ cells. Muscle cells contain contractile filaments that move past each other and change the size of the cell. They are classified as skeletal, cardiac, or smooth muscles. Their function is to...
mantle
Mantle (mollusc)
The mantle is a significant part of the anatomy of molluscs: it is the dorsal body wall which covers the visceral mass and usually protrudes in the form of flaps well beyond the visceral mass itself.In many, but by no means all, species of molluscs, the epidermis of the mantle secretes...
covered by an outer and inner skin (tunic). Traces of a criss-cross pattern composed of collagen
Collagen
Collagen is a group of naturally occurring proteins found in animals, especially in the flesh and connective tissues of mammals. It is the main component of connective tissue, and is the most abundant protein in mammals, making up about 25% to 35% of the whole-body protein content...
fibers have been observed in the surface of some well-preserved fossils. The cross section of the exceptionally preserved body wall of a specimen from the Oxford Clay
Oxford Clay
The Oxford Clay Formation is a Jurassic marine sedimentary rock formation underlying much of southeast England, from as far west as Dorset and as far north as Yorkshire. The Oxford Clay is of middle Callovian to lower Oxfordian age and comprises 2 main facies. The lower facies comprises the...
formations also reveals alternating bands of concentrically and radially oriented body fibers. They imply that Belemnotheutis were powerful swimmers and agile predators, similar to modern shallow-water squid species. The animal reached 10 to 30 cm (3.9 to 11.8 in) in length, including its arms. The body diameter was around 12 to 14% of the mantle length. At the center of the dorsal surface of the rostrum is a narrow V-shaped groove running about 3/5ths the length of the phragmocone from the apex, with two rounded ridges at its left and right sides. These grooves are one of the most distinctive features of the Belemnotheutidae and are theorized to have served as attachments to terminal oval or oar-shaped fins like in some modern squids. The siphuncle
Siphuncle
The siphuncle is a strand of tissue passing longitudinally through the shell of a cephalopod mollusk. Only cephalopods with chambered shells have siphuncles, such as the extinct ammonites and belemnites, and the living nautiluses, cuttlefish, and Spirula...
is marginal and located ventrally. Directly in front of the phragmocone was an ink sac
Ink sac
With the exception of nocturnal and very deep water cephalopods, all coeloids which dwell in light conditions have an ink sac, which can be used to expel a cloud of dark ink to confuse predators. This sac is a muscular bag which originated as an extension of the hind gut...
that could reach 25 mm (0.984251968503937 in) long in large specimens. Intestinal casts (cololites) as well as the orientations and positions of fossilized remains reveal that the animal preyed on fish and other coleoids in life. Their great abundance in certain formations indicate that Belemnotheutis were highly gregarious animals, congregating in large monospecific or polyspecific shoals.
Fossil ink
Fossilized ink chambersCephalopod ink
Cephalopod ink is a dark pigment released into water by most species of cephalopod, usually as an escape mechanism. All cephalopods, with the exception of the Nautilidae and the species of octopus belonging to the suborder Cirrina, are able to release ink....
of belemnites were first discovered by the famous British
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
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...
and paleontologist Mary Anning
Mary Anning
Mary Anning was a British fossil collector, dealer and palaeontologist who became known around the world for a number of important finds she made in the Jurassic age marine fossil beds at Lyme Regis where she lived...
in 1826. She and her friend Elizabeth Philpot
Elizabeth Philpot
Elizabeth Philpot was an early 19th century British fossil collector, amateur palaeontologist and artist who collected fossils from the cliffs around Lyme Regis in Dorset on the southern coast of England. She is best known today for her collaboration and friendship with the well known fossil...
, another fossil collector, along with her brother Joseph Anning, succeeded in revivifying the ink and used it to illustrate ichthyosaur
Ichthyosaur
Ichthyosaurs were giant marine reptiles that resembled fish and dolphins...
and 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...
fossils. The ink recovered from such fossils were also used to draw fossil ichthyosaurs by Sir Henry Thomas De la Beche
Henry De la Beche
Sir Henry Thomas De la Beche FRS was an English geologist and palaeontologist who helped pioneer early geological survey methods.-Biography:...
, a friend and supporter of Mary Anning.
In 2008, an excavation team led by the British Geological Survey
British Geological Survey
The British Geological Survey is a partly publicly funded body which aims to advance geoscientific knowledge of the United Kingdom landmass and its continental shelf by means of systematic surveying, monitoring and research. The BGS headquarters are in Keyworth, Nottinghamshire, but other centres...
in Christian Malford
Christian Malford
Christian Malford is a small village in the county of Wiltshire in England. The unusual name is evidently a corruption of Christ mal Ford, Old English moel, mal being a mark: "Christ’s mal" is Christ’s mark or sign, the cross. The name signified "Cross Ford". Deeds from Glastonbury Abbey cartulary...
recovered fossilized ink sacs from several remarkably preserved remains of Belemnotheutis antiquus in the Oxford Clay Formation. The specimens were fossilized rapidly in apatite
Apatite
Apatite is a group of phosphate minerals, usually referring to hydroxylapatite, fluorapatite, chlorapatite and bromapatite, named for high concentrations of OH−, F−, Cl− or Br− ions, respectively, in the crystal...
(calcium phosphate) through a process paleontologist Dr. Phil Wilby called "The Medusa Effect". By mixing it with ammonia
Ammonia
Ammonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...
solution, the team was able to return the ink to its liquid form. Bringing to mind the 19th century practices of the aforementioned early paleontologists, they used the ~150 million year old ink to draw a replica of the original illustration of Belemnotheutis as drawn by Joseph Channing Pearce. Dr. Wilby called the drawing "the ultimate self-portrait".
History and controversy
Belemnotheutis was first described by the amateur paleontologist Joseph Channing Pearce in 1842 in WiltshireWiltshire
Wiltshire is a ceremonial county in South West England. It is landlocked and borders the counties of Dorset, Somerset, Hampshire, Gloucestershire, Oxfordshire and Berkshire. It contains the unitary authority of Swindon and covers...
, South West England
South West England
South West England is one of the regions of England defined by the Government of the United Kingdom for statistical and other purposes. It is the largest such region in area, covering and comprising Bristol, Gloucestershire, Somerset, Dorset, Wiltshire, Devon, Cornwall and the Isles of Scilly. ...
, two years after excavations from the construction of the Great Western Railway
Great Western Railway
The Great Western Railway was a British railway company that linked London with the south-west and west of England and most of Wales. It was founded in 1833, received its enabling Act of Parliament in 1835 and ran its first trains in 1838...
uncovered parts of the Oxford Clay formation. It is unknown why he chose the spelling Belemnotheutis rather than what common convention would have dictated - Belemnoteuthis. He described his discovery to the Geological Society of London
Geological Society of London
The Geological Society of London is a learned society based in the United Kingdom with the aim of "investigating the mineral structure of the Earth"...
in the same year.
In 1843, Richard Owen
Richard Owen
Sir Richard Owen, FRS KCB was an English biologist, comparative anatomist and palaeontologist.Owen is probably best remembered today for coining the word Dinosauria and for his outspoken opposition to Charles Darwin's theory of evolution by natural selection...
acquired specimens of Belemnotheutis from the same locality from another paleontologist, Samuel Peace Pratt. He formally published a paper on 1844 (On the Belemnites, Philosophical Transactions of the Royal Society
Philosophical Transactions of the Royal Society B: Biological Sciences
Philosophical Transactions of the Royal Society B: Biological Sciences is a peer-reviewed scientific journal published by the Royal Society. The ISO abbreviation for the journal is Phil. Trans. R. Soc...
), naming the specimens Belemnites owenii Pratt, after himself and crediting Pratt with the discovery while failing to mention Pearce. He believed that the specimens were of the genus Belemnites whose typically lengthy rostra simply got separated. He sent a copy of the paper to Pearce in the same year, proving that he was actually aware of Pearce's earlier description but had deliberately omitted any mention of him. Pearce responded by stating that examination by another paleontologist James Scott Bowerbank
James Scott Bowerbank
James Scott Bowerbank FRS was a British naturalist and palaeontologist.-Biography:Bowerbank was born in Bishopsgate, London, and succeeded in conjunction with his brother to his father's distillery, in which he was actively engaged until 1847.In early years astronomy and natural history,...
, supported his belief that fossils did not possess the bullet-shaped guards typical of Belemnites but instead had rostra in the form of very thin sheaths. Bowerbanks confirmed this assertion but supported Owen's assignment of Belemnites, saying that the presence of very short rostra did not justify the classification of Belemnotheutis as a separate genus from Belemnites.
Owen received a Royal Medal
Royal Medal
The Royal Medal, also known as The Queen's Medal, is a silver-gilt medal awarded each year by the Royal Society, two for "the most important contributions to the advancement of natural knowledge" and one for "distinguished contributions in the applied sciences" made within the Commonwealth of...
from the Royal Society
Royal Society
The Royal Society of London for Improving Natural Knowledge, known simply as the Royal Society, is a learned society for science, and is possibly the oldest such society in existence. Founded in November 1660, it was granted a Royal Charter by King Charles II as the "Royal Society of London"...
in 1846 for the 1844 paper, further inducing Pearce to protest what he viewed as erroneous descriptions of the specimens. In 1847, the London Geological Journal published a paper by Pearce of his objections to Owen's paper. At the same time the editor of the paper and another paleontologist, Edward Charlesworth, published an editorial criticizing Owen for deliberately failing to credit Pearce with the discovery of Belemnotheutis, as well as his apparent disregard to the opinions of less well-known paleontologists like Pearce. This was also the first time that Pearce described the specific epithet antiquus to the fossils. Pearce died later in the same year in May 1847 taking no further part in what was to become a controversy. Shortly after his death, the same paper published the support of William Cunnington
William Cunnington
William Cunnington was a pioneering English antiquarian and archaeologist of the late eighteenth and early nineteenth century. His work centred on excavating the barrows of Salisbury Plain. The first recorded excavations at Stonehenge were done by William Cunnington & Richard Colt Hoare in 1798...
, a 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...
, for this description as opposed to Owen's conclusions.
In 1848, Gideon Mantell
Gideon Mantell
Gideon Algernon Mantell MRCS FRS was an English obstetrician, geologist and palaeontologist...
read a description of Belemnotheutis specimens recovered by his son Reginald Neville Mantell to the Royal Society. His descriptions supported that of Pearce's views and held that the differences between belemnites and Belemnotheutis were enough to justify it being a separate genus. He also described the characteristic groove on the apical dorsal surface of the Belemnotheutis for the first time (structures which Owen had attributed as artifacts of crushing). He had expected Owen, who was present during the session, to support this amendment. Instead, Owen ridiculed Mantell, further aggravating the famous feud between the two.
Mantell continued to assert his position until his death in 1852, gaining supporters in other eminent paleontologists like Edward Forbes
Edward Forbes
Professor Edward Forbes FRS, FGS was a Manx naturalist.-Early years:Forbes was born at Douglas, in the Isle of Man. While still a child, when not engaged in reading, or in the writing of verses and drawing of caricatures, he occupied himself with the collecting of insects, shells, minerals,...
and Charles Lyell
Charles Lyell
Sir Charles Lyell, 1st Baronet, Kt FRS was a British lawyer and the foremost geologist of his day. He is best known as the author of Principles of Geology, which popularised James Hutton's concepts of uniformitarianism – the idea that the earth was shaped by slow-moving forces still in operation...
against Owen with regards to the true morphology of Belemnotheutis. By then the hostility between Owen and Mantell had escalated, Owen going so far as to oppose the awarding of the Royal Medal to Mantell for his work in 1849. Mantell did eventually receive the Royal Medal for his work on 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...
to which Owen had attempted to claim another authority much in the same way that he had named Belemnotheutis after himself.
In 1860, three years after Mantell's death, Owen eventually published an amendment to his earlier descriptions. He acknowledged that Belemnotheutis indeed had very thin rostra and was distinct from the genus Belemnites. He did so only after other prominent authorities described the very similar Acanthoteuthis
Acanthoteuthis
Acanthoteuthis is a belemnite genus, a squid-like cephalopod with an internal shell from the Late Jurassic Epoch, related to modern coleoids....
and were considering Belemnotheutis as its synonym. However, he never recanted his earlier criticism of both Pearce and Mantell.
Distribution and geological time range
Belemnotheutis existed during the late Middle JurassicMiddle Jurassic
The Middle Jurassic is the second epoch of the Jurassic Period. It lasted from 176-161 million years ago. In European lithostratigraphy, rocks of this Middle Jurassic age are called the Dogger....
to the Upper Jurassic epoch
Epoch (geology)
An epoch is a subdivision of the geologic timescale based on rock layering. In order, the higher subdivisions are periods, eras and eons. We are currently living in the Holocene epoch...
, from the Callovian
Callovian
In the geologic timescale, the Callovian is an age or stage in the Middle Jurassic, lasting between 164.7 ± 4.0 Ma and 161.2 ± 4.0 Ma. It is the last stage of the Middle Jurassic, following the Bathonian and preceding the Oxfordian....
age (164.7 to 161.2 mya) to the Kimmeridgian
Kimmeridgian
In the geologic timescale, the Kimmeridgian is an age or stage in the Late or Upper Jurassic epoch or series. It spans the time between 155.7 ± 4 Ma and 150.8 ± 4 Ma . The Kimmeridgian follows the Oxfordian and precedes the Tithonian....
age (155.7 to 150.8 mya). The belemnotheutid Acanthoteuthis
Acanthoteuthis
Acanthoteuthis is a belemnite genus, a squid-like cephalopod with an internal shell from the Late Jurassic Epoch, related to modern coleoids....
, a close relative which is treated by some paleontologists as synonymous with Belemnotheutis, is known to have existed from as early as the Callovian
Callovian
In the geologic timescale, the Callovian is an age or stage in the Middle Jurassic, lasting between 164.7 ± 4.0 Ma and 161.2 ± 4.0 Ma. It is the last stage of the Middle Jurassic, following the Bathonian and preceding the Oxfordian....
age (164.7 to 161.2 mya) of the Middle Jurassic
Middle Jurassic
The Middle Jurassic is the second epoch of the Jurassic Period. It lasted from 176-161 million years ago. In European lithostratigraphy, rocks of this Middle Jurassic age are called the Dogger....
epoch to as late as the Aptian
Aptian
The Aptian is an age in the geologic timescale or a stage in the stratigraphic column. It is a subdivision of the Early or Lower Cretaceous epoch or series and encompasses the time from 125.0 ± 1.0 Ma to 112.0 ± 1.0 Ma , approximately...
age (125 to 112 mya) of the Lower Cretaceous epoch. The earliest known possible remains of belemnotheutids (genera Chitinobelus and Chondroteuthis
Chondroteuthis
Chondroteuthis is a genus of belemnite, an extinct group of cephalopods....
) come from the Lower Jurassic, from phragmocones and rostra recovered from 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...
formations in Dumbleton
Dumbleton
Dumbleton is a village in the English county of Gloucestershire. The village is roughly 20 miles from Gloucester and 50 miles from Bristol.The village is known to have existed in the time of Ethelred I who granted land to Abingdon Abbey, and it is mentioned in the Domesday Book.St Peter's church is...
, Gloucestershire
Gloucestershire
Gloucestershire is a county in South West England. The county comprises part of the Cotswold Hills, part of the flat fertile valley of the River Severn, and the entire Forest of Dean....
, and 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...
, Somerset
Somerset
The ceremonial and non-metropolitan county of Somerset in South West England borders Bristol and Gloucestershire to the north, Wiltshire to the east, Dorset to the south-east, and Devon to the south-west. It is partly bounded to the north and west by the Bristol Channel and the estuary of the...
, 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...
. However, these remains seem to have possessed the typical calcitic
Calcite
Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate . The other polymorphs are the minerals aragonite and vaterite. Aragonite will change to calcite at 380-470°C, and vaterite is even less stable.-Properties:...
rostra of true belemnites rather than the characteristic aragonitic rostra of belemnotheutids.
Belemnotheutis serve as index fossil
Index fossil
Index fossils are fossils used to define and identify geologic periods . They work on the premise that, although different sediments may look different depending on the conditions under which they were laid down, they may include the remains of the same species of fossil...
s. They are mostly found in Jurassic
Jurassic
The Jurassic is a geologic period and system that extends from about Mya to Mya, that is, from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic era, also known as the age of reptiles. The start of the period is marked by...
formations like the Kimmeridge Clay
Kimmeridge Clay
The Kimmeridge Clay Formation is a sedimentary deposit of fossiliferous marine clay which is of Jurassic age. It occurs in Europe.Kimmeridge Clay is arguably the most economically important unit of rocks in the whole of Europe, being the major source rock for oil fields in the North Sea hydrocarbon...
formation, the Oxford Clay
Oxford Clay
The Oxford Clay Formation is a Jurassic marine sedimentary rock formation underlying much of southeast England, from as far west as Dorset and as far north as Yorkshire. The Oxford Clay is of middle Callovian to lower Oxfordian age and comprises 2 main facies. The lower facies comprises the...
formation, and the Solnhofen Limestone
Solnhofen limestone
The Solnhofen Plattenkalk is a Jurassic Konservat-Lagerstätte that preserves a rare assemblage of fossilized organisms, including highly detailed imprints of soft bodied organisms such as sea jellies...
formation. Their geographic range, thus far, is confined to 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...
.
Taxonomy and nomenclature
Belemnotheutis are coleoids belonging to the familyFamily (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Belemnotheutidae. Belemnotheutis and other belemnotheutids are considered by some paleontologists to be distinct from true belemnites (suborder Belemnitina
Belemnitina
Belemnitina is a genus of belemnite, an extinct group of cephalopods....
). Most authorities like Jeletzky (1966), Bandel and Kulicki (1988), and Peter Doyle (1990) classify it under Belemnitida in the suborder Belemnotheutina (the classification used by this article). Others like Donovan (1977) and Engeser and Reitner (1981) classify it as a distinct order, Belemnotheutida, based on the aragonitic constitution of the rostra, the shape of the proostraca, protoconchs, and the arm crowns, among other morphological factors.
Belemnotheutis has been continually spelled as Belemnoteuthis by authors who believed that Pearce had made an honest mistake in naming the specimens. In 1999, D.T. Donovan and M.D. Crane succeeded in convincing the International Commission on Zoological Nomenclature
International Commission on Zoological Nomenclature
The International Commission on Zoological Nomenclature is an organization dedicated to "achieving stability and sense in the scientific naming of animals". Founded in 1895, it currently comprises 28 members from 20 countries, mainly practicing zoological taxonomists...
that the spelling was intentional, citing historical usage of the spelling Greek θευτίς (theutis) as a valid variant of the usual τευθίς (teuthis, 'squid'). Subsequently, the accepted spelling
International Code of Zoological Nomenclature
The International Code of Zoological Nomenclature is a widely accepted convention in zoology that rules the formal scientific naming of organisms treated as animals...
is now formally Belemnotheutis.
Species
The following is a list of species described under the genus Belemnotheutis.- Belemnotheutis antiquus Pearce, 1842
- Belemnotheutis polonica Makowski, 1952
- Belemnotheutis mayri Engeser & Reitner, 1981
Belemnotheutis montefiorei has been transferred to the genus Phragmoteuthis
Phragmoteuthis
Phragmoteuthis is a genus of coleoid cephalopod known from the late Triassic to the lower Jurassic. Its soft tissue has been preserved; some specimens contain intact ink sacs, and others, gills. It had an internal phragmocone and ten arms....
and B. rosenkrantzi to the genus Groenlandibelus.
External links
- A drawing of Belemnotheutis drawn in fossil ink British Geological Survey.