Rhomaleosaurus Cramptoni
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''Rhomaleosaurus'' (meaning "strong lizard") is an
extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...
genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...
of
Early Jurassic The Early Jurassic Epoch (geology), Epoch (in chronostratigraphy corresponding to the Lower Jurassic series (stratigraphy), Series) is the earliest of three epochs of the Jurassic Period. The Early Jurassic starts immediately after the Triassicâ ...
(
Toarcian The Toarcian is, in the International Commission on Stratigraphy, ICS' geologic timescale, an age (geology), age and stage (stratigraphy), stage in the Early Jurassic, Early or Lower Jurassic. It spans the time between 184.2 Megaannum, Ma (million ...
age Age or AGE may refer to: Time and its effects * Age, the amount of time someone has been alive or something has existed ** East Asian age reckoning, an Asian system of marking age starting at 1 * Ageing or aging, the process of becoming older ...
, about 183 to 175.6 million years ago)
rhomaleosaurid Rhomaleosauridae is a family of plesiosaurs from the Earliest Jurassic to the latest Middle Jurassic (Hettangian to Callovian stages) of Europe, North America, South America and possibly Asia. Most rhomaleosaurids are known from England, many sp ...
pliosauroid known from
Northamptonshire Northamptonshire ( ; abbreviated Northants.) is a Ceremonial counties of England, ceremonial county in the East Midlands of England. It is bordered by Leicestershire, Rutland and Lincolnshire to the north, Cambridgeshire to the east, Bedfordshi ...
and from
Yorkshire Yorkshire ( ) is an area of Northern England which was History of Yorkshire, historically a county. Despite no longer being used for administration, Yorkshire retains a strong regional identity. The county was named after its county town, the ...
of the
United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Northwestern Europe, off the coast of European mainland, the continental mainland. It comprises England, Scotlan ...
. It was first named by
Harry Seeley Harry Govier Seeley (18 February 1839 – 8 January 1909) was a British paleontologist. Early life Seeley was born in London on 18 February 1839, the second son of Richard Hovill Seeley, a goldsmith, and his second wife Mary Govier. When his fa ...
in
1874 Events January * January 1 – New York City annexes The Bronx. * January 2 – Ignacio María González becomes head of state of the Dominican Republic for the first time. * January 3 – Third Carlist War: Battle of Caspe &n ...
and the
type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...
is ''Rhomaleosaurus cramptoni''. It was one of the earliest large marine reptile predators which hunted in the seas of
Mesozoic era The Mesozoic Era is the era of Earth's geological history, lasting from about , comprising the Triassic, Jurassic and Cretaceous Periods. It is characterized by the dominance of archosaurian reptiles such as the dinosaurs, and of gymnosperms s ...
, measuring about long. Like other pliosaurs, ''Rhomaleosaurus'' fed on
ichthyosaurs Ichthyosauria is an taxonomy (biology), order of large extinction, extinct marine reptiles sometimes referred to as "ichthyosaurs", although the term is also used for wider clades in which the order resides. Ichthyosaurians thrived during much of ...
,
ammonites Ammonoids are extinct, (typically) coiled-shelled cephalopods comprising the subclass Ammonoidea. They are more closely related to living octopuses, squid, and cuttlefish (which comprise the clade Coleoidea) than they are to nautiluses (family N ...
and other
plesiosaurs The Plesiosauria or plesiosaurs are an Order (biology), order or clade of extinct Mesozoic marine reptiles, belonging to the Sauropterygia. Plesiosaurs first appeared in the latest Triassic Period (geology), Period, possibly in the Rhaetian st ...
.


Species


''R. cramptoni''

In July 1848, a fossil of a large plesiosaur was unearthed in an
alum An alum () is a type of chemical compound, usually a hydrated double salt, double sulfate salt (chemistry), salt of aluminium with the general chemical formula, formula , such that is a valence (chemistry), monovalent cation such as potassium ...
quarry at
Kettleness Kettleness, is a hamlet in the county of North Yorkshire, England. The settlement only consists of half-a-dozen houses, but up until the early 19th century, it was a much larger village. However, most of that village, which was on the headland, ...
, near Whitby, in Yorkshire, England. It was collected from the ''A. bifrons'' ammonite zone of the
Whitby Mudstone Formation The Whitby Mudstone is a Toarcian (Early Jurassic; ''Falciferum''-''Bifrons'' in regional chronostratigraphy) geological formation in Yorkshire and Worcestershire, England.Toarcian The Toarcian is, in the International Commission on Stratigraphy, ICS' geologic timescale, an age (geology), age and stage (stratigraphy), stage in the Early Jurassic, Early or Lower Jurassic. It spans the time between 184.2 Megaannum, Ma (million ...
age, about 183 to 180 million years ago. The complete
skeleton A skeleton is the structural frame that supports the body of most animals. There are several types of skeletons, including the exoskeleton, which is a rigid outer shell that holds up an organism's shape; the endoskeleton, a rigid internal fra ...
which preserved the
skull The skull, or cranium, is typically a bony enclosure around the brain of a vertebrate. In some fish, and amphibians, the skull is of cartilage. The skull is at the head end of the vertebrate. In the human, the skull comprises two prominent ...
, NMING F8785, was kept for five years at
Mulgrave Castle Mulgrave Castle refers to one of three structures on the same property in Lythe, near Whitby, North Yorkshire, England. One of these, known as the "old" or "ancient" castle, was by legend founded by Wade (folklore), Wada, a 6th-century ruler of ...
, which was then owned by the
Marquess of Normanby Marquess of Normanby is a title that has been created twice, once in the Peerage of England and once in the Peerage of the United Kingdom. The first creation came in 1694 in the Peerage of England in favour of John Sheffield, 3rd Earl of Mul ...
. In 1853, the Marquess introduced the interesting finding to the eminent Irish surgeon and anatomist,
Sir Philip Crampton Sir Philip Crampton, 1st Baronet, FRS MRCSI MRIA (7 June 1777 – 10 June 1858) was an eminent Irish surgeon and anatomist. He was President of the Royal College of Surgeons in Ireland (RCSI) in 1811, 1820, 1844 and 1855. Life Crampton was b ...
. The same year, Crampton transferred the fossil to
Dublin Dublin is the capital and largest city of Republic of Ireland, Ireland. Situated on Dublin Bay at the mouth of the River Liffey, it is in the Provinces of Ireland, province of Leinster, and is bordered on the south by the Dublin Mountains, pa ...
to be displayed as a centrepiece at the 1853
British Association The British Science Association (BSA) is a charity and learned society founded in 1831 to aid in the promotion and development of science. Until 2009 it was known as the British Association for the Advancement of Science (BA). The current Chief ...
annual meeting. The
Zoological Society of Ireland The Zoological Society of Ireland (ZSI) is the body responsible for running Dublin Zoo, where it is based, and Fota Wildlife Park in County Cork. It is the successor to the Royal Zoological Society of Ireland (RZSI), a learned society for the ...
built a specially constructed building to house the large reptile. After a decade, still remaining undescribed, the specimen moved in the
Royal Dublin Society The Royal Dublin Society (RDS) () is an Irish philanthropic organisation and members club which was founded as the 'Dublin Society' on 25 June 1731 with the aim to see Ireland thrive culturally and economically. It was long active as a learned ...
museum and was officially described by
Alexander Carte Alexander Carte Doctor of Medicine, MD, Royal College of Surgeons in Ireland, FRCSI, Royal Irish Academy, MRIA (11 August 1805 – 25 September 1881) was an Ireland, Irish zoologist and paleontology, palaeontologist and was first director Natur ...
and W. H. Bailey as a new species of ''
Plesiosaurus ''Plesiosaurus'' (Greek: ' ('), near to + ' ('), lizard) is a genus of extinct, large marine sauropterygian reptile that lived during the Early Jurassic. It is known by nearly complete skeletons from the Lias of England. It is distinguishable by ...
''. Carte and Bailey named the species ''Plesiosaurus cramptoni'' after the Irish scientist, Sir Philip Crampton. In 1874, the British geologist
Harry Govier Seeley Harry Govier Seeley (18 February 1839 – 8 January 1909) was a British paleontologist. Early life Seeley was born in London on 18 February 1839, the second son of Richard Hovill Seeley, a goldsmith, and his second wife Mary Govier. When his fa ...
, based on this finding, which is now known as the
type genus In biological taxonomy, the type genus (''genus typica'') is the genus which defines a biological family and the root of the family name. Zoological nomenclature According to the International Code of Zoological Nomenclature, "The name-bearin ...
of the family
Rhomaleosauridae Rhomaleosauridae is a family of plesiosaurs from the Earliest Jurassic to the latest Middle Jurassic (Hettangian to Callovian stages) of Europe, North America, South America and possibly Asia. Most rhomaleosaurids are known from England, many s ...
, recognized and erected a new genus establishing ''Rhomaleosaurus''. Only in 2006 the
skull The skull, or cranium, is typically a bony enclosure around the brain of a vertebrate. In some fish, and amphibians, the skull is of cartilage. The skull is at the head end of the vertebrate. In the human, the skull comprises two prominent ...
of this specimen was finally prepared which enabled a restudy of this genus. Casts of the holotype specimen are on display at the Natural History Museum, London (NHMUK PV R 34) and Bath Royal Literary and Scientific Institution.


''R. propinquus''

''R. propinquus'' is known from the
holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...
WM 852.S, articulated almost complete
skeleton A skeleton is the structural frame that supports the body of most animals. There are several types of skeletons, including the exoskeleton, which is a rigid outer shell that holds up an organism's shape; the endoskeleton, a rigid internal fra ...
which preserved the
skull The skull, or cranium, is typically a bony enclosure around the brain of a vertebrate. In some fish, and amphibians, the skull is of cartilage. The skull is at the head end of the vertebrate. In the human, the skull comprises two prominent ...
, exposed in
dorsal Dorsal (from Latin ''dorsum'' ‘back’) may refer to: * Dorsal (anatomy), an anatomical term of location referring to the back or upper side of an organism or parts of an organism * Dorsal, positioned on top of an aircraft's fuselage The fus ...
view. It was collected from the ''A. serpentines'' ammonoid zone, of the
Whitby Mudstone Formation The Whitby Mudstone is a Toarcian (Early Jurassic; ''Falciferum''-''Bifrons'' in regional chronostratigraphy) geological formation in Yorkshire and Worcestershire, England.million years ago Million years ago, abbreviated as Mya, Myr (megayear) or Ma (megaannum), is a unit of time equal to (i.e. years), or approximately 31.6 teraseconds. Usage Myr is in common use in fields such as Earth science and cosmology. Myr is also used w ...
. ''R. propinquus'' was first named by Tate and Blake in
1876 Events January * January 1 ** The Reichsbank opens in Berlin. ** The Bass Brewery Red Triangle becomes the world's first registered trademark symbol. *January 27 – The Northampton Bank robbery occurs in Massachusetts. February * Febr ...
as a new species of ''
Plesiosaurus ''Plesiosaurus'' (Greek: ' ('), near to + ' ('), lizard) is a genus of extinct, large marine sauropterygian reptile that lived during the Early Jurassic. It is known by nearly complete skeletons from the Lias of England. It is distinguishable by ...
''. Watson (1910) redescribed it as a species of ''Rhomaleosaurus''. Adam S. Smith (2007), in his thesis on the anatomy and classification of the family
Rhomaleosauridae Rhomaleosauridae is a family of plesiosaurs from the Earliest Jurassic to the latest Middle Jurassic (Hettangian to Callovian stages) of Europe, North America, South America and possibly Asia. Most rhomaleosaurids are known from England, many s ...
, suggested that ''R. propinquus'', is a junior synonym of ''Rhomaleosaurus zetlandicus''. Smith and Gareth J. Dyke (2008) considered this species to be valid.


''R. thorntoni''

''R. thorntoni'' is known from the
holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...
NHMUK PV R 4853, three-dimensional, partially complete skeleton which preserved most of the skull and
mandible In jawed vertebrates, the mandible (from the Latin ''mandibula'', 'for chewing'), lower jaw, or jawbone is a bone that makes up the lowerand typically more mobilecomponent of the mouth (the upper jaw being known as the maxilla). The jawbone i ...
s. It was collected by Henry Gerard Thornton from Kingsthorp of
Northamptonshire Northamptonshire ( ; abbreviated Northants.) is a Ceremonial counties of England, ceremonial county in the East Midlands of England. It is bordered by Leicestershire, Rutland and Lincolnshire to the north, Cambridgeshire to the east, Bedfordshi ...
, dating to the Toarcian stage. It is the only well-known British Toarcian rhomaleosaurid discovered away from the Yorkshire coast, to date. ''R. thorntoni'' was first named by Andrews in
1922 Events January * January 7 – Dáil Éireann (Irish Republic), Dáil Éireann, the parliament of the Irish Republic, ratifies the Anglo-Irish Treaty by 64–57 votes. * January 10 – Arthur Griffith is elected President of Dáil Éirean ...
and later revised by Cruickshank (1996) as a junior synonym of ''R. cramptoni'', alongside ''R. zetlandicus''. Adam S. Smith (2007) and Smith and Gareth J. Dyke (2008) considered this species to be valid.


''R. zetlandicus''

''R. zetlandicus'' is known from the
holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...
YORYM G503 (pictured), a nearly complete skull and
vertebral column The spinal column, also known as the vertebral column, spine or backbone, is the core part of the axial skeleton in vertebrates. The vertebral column is the defining and eponymous characteristic of the vertebrate. The spinal column is a segmente ...
in association with parts of the
limb Limb may refer to: Science and technology *Limb (anatomy), an appendage of a human or animal *Limb, a large or main branch of a tree *Limb, in astronomy, the curved edge of the apparent disk of a celestial body, e.g. lunar limb *Limb, in botany, t ...
s. It was in the early 1850s collected from the Alum Shale of Whitby Mudstone Formation, Yorkshire, dating from the Toarcian stage and donated in 1852 to the Yorkshire Philosophical Society by
Lawrence Dundas, 1st Earl of Zetland Lawrence Dundas, 1st Earl of Zetland (10 April 1766 – 19 February 1839) was a British politician and peer who sat in the House of Commons from 1790 to 1820 when he was raised to the peerage of the United Kingdom. Early life Dundas was the ...
, the Loftus mine owner. ''R. zetlandicus'' was first validly named by Phillips in
1854 Events January–March * January 4 – The McDonald Islands are discovered by Captain William McDonald aboard the ''Samarang''. * January 6 – The fictional detective Sherlock Holmes is perhaps born. * January 9 – The Te ...
and its skull was described in detail by Michael Alan Taylor in 1992. Later the taxon was revised by Cruickshank (1996) as a senior synonym of ''R. cramptoni'', ''R. thorntoni'' being a junior synonym. Adam S. Smith (2007) and Smith and Gareth J. Dyke (2008) considered this species to be valid.


Reassigned species

Through the years, various species have been referred to as ''Rhomaleosaurus''. However, according to Smith (2007), in his thesis on the anatomy and classification of the family
Rhomaleosauridae Rhomaleosauridae is a family of plesiosaurs from the Earliest Jurassic to the latest Middle Jurassic (Hettangian to Callovian stages) of Europe, North America, South America and possibly Asia. Most rhomaleosaurids are known from England, many s ...
, the genus ''Rhomaleosaurus'' has only three valid species: ''R. cramptoni'', ''R. thorntoni'' and ''R. zetlandicus''. Smith and Dyke (2008) also recognized ''R. propinquus'' as valid. Other species that previously fell under this genus were: ''R. megacephalus'' and ''R. victor''. Smith (2007) and Smith and Dyke (2008) pointed out that these species do not belong to ''Rhomaleosaurus'', as ''R. megacephalus'' is referred to ''
Eurycleidus ''Eurycleidus'' is an extinct genus of large-bodied rhomaleosaurid known from the Early Jurassic period (most likely earliest Hettangian stage) of the United Kingdom. It contains a single species, ''E. arcuatus''. Discovery and naming The cu ...
'' (or to a new genus by Smith and Dyke (2008)) and ''R. victor'' represents a new genus named ''
Meyerasaurus ''Meyerasaurus'' is an extinct genus of rhomaleosaurid plesiosaur known from the Early Jurassic of Holzmaden, Baden-Württemberg in southwestern Germany. Discovery Between Holzmaden and Zell unter Aichelberg, a chalkstone and shale quarry was ...
'' by Smith and Vincent in 2010.
Cladistic Cladistics ( ; from Ancient Greek 'branch') is an approach to biological classification in which organisms are categorized in groups ("clades") based on hypotheses of most recent common ancestry. The evidence for hypothesized relationships is ...
analyses by Ketchum & Benson, 2010, Benson ''et al.'', 2011 and Ketchum & Benson, 2011 found ''R. megacephalus'' to be basal to the clade containing ''Rhomaleosaurus'' and ''Eurycleidus'', thus it should be in its own genus as suggested by Smith and Dyke (2008). Following this, it has been placed in its own genus, ''
Atychodracon ''Atychodracon'' is an extinct genus of rhomaleosaurid plesiosaurian known from the Late Triassic - Early Jurassic boundary (probably early Hettangian stage) of England. It contains a single species, ''Atychodracon megacephalus'', named in 184 ...
''. (Smith, 2015).


''Thaumatosaurus''

The name '' Thaumatosaurus'', which means 'wonder reptile', belonged to a genus of plesiosaur that was described by palaeontologist
Christian Erich Hermann von Meyer Christian Erich Hermann von Meyer (3 September 1801 – 2 April 1869), known as Hermann von Meyer, was a German palaeontologist. He was awarded the 1858 Wollaston medal by the Geological Society of London. Life He was born in Frankfurt am ...
, back in 1841. Meyer described the species ''Thaumatosaurus oolithicus'' based on partial skull, vertebral and limb remains, that were found in the
Posidonia Shale The Posidonia Shale (, also called Schistes Bitumineux in Luxembourg) geologically known as the Sachrang Formation, is an Early Jurassic (Early to Late Toarcian) geological formation in Germany, northern Switzerland, northwestern Austria, souther ...
of
Holzmaden Holzmaden is a town in Baden-Württemberg, Germany that lies between Stuttgart and Ulm. Holzmaden is 4 km south-east from Kirchheim unter Teck and 19 km south-east of Esslingen am Neckar. The A 8 runs south from Holzmaden. The town a ...
,
Baden-Württemberg Baden-Württemberg ( ; ), commonly shortened to BW or BaWü, is a states of Germany, German state () in Southwest Germany, east of the Rhine, which forms the southern part of Germany's western border with France. With more than 11.07 million i ...
,
Germany Germany, officially the Federal Republic of Germany, is a country in Central Europe. It lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen States of Germany, constituent states have a total popu ...
. In 1856, Meyer published a full description of ''Thaumatosaurus'' and later provided figures of the specimen.
Richard Lydekker Richard Lydekker (; 25 July 1849 – 16 April 1915) was a British naturalist, geologist and writer of numerous books on natural history. He was known for his contributions to zoology, paleontology, and biogeography. He worked extensively in cata ...
(1889) regarded ''Rhomaleosaurus'' as a synonym of ''Thaumatosaurus'' because Richard Lydekker and Harry G. Seeley "refused steadfastly to recognize the generic and specific names proposed by one another". Lydekker referred continuously to the name ''Thaumatosaurus'', instead of ''Rhomaleosaurus''. Fraas (1910) recognized both generic names in his original description of ''R. victor'' (now ''
Meyerasaurus ''Meyerasaurus'' is an extinct genus of rhomaleosaurid plesiosaur known from the Early Jurassic of Holzmaden, Baden-Württemberg in southwestern Germany. Discovery Between Holzmaden and Zell unter Aichelberg, a chalkstone and shale quarry was ...
''), but referring to the new species "Thaumatosaurus" victor. Many other researchers adopted the name "Thaumatosaurus". Today this taxon is regarded as a
nomen dubium In binomial nomenclature, a ''nomen dubium'' (Latin for "doubtful name", plural ''nomina dubia'') is a scientific name that is of unknown or doubtful application. Zoology In case of a ''nomen dubium,'' it may be impossible to determine whether a ...
because the holotype can be referred to Pliosauroidea indet at best. The diagnostic specimens which previously were regarded as ''Thaumatosauruss specimens, now represent the holotypes of ''
Eurycleidus ''Eurycleidus'' is an extinct genus of large-bodied rhomaleosaurid known from the Early Jurassic period (most likely earliest Hettangian stage) of the United Kingdom. It contains a single species, ''E. arcuatus''. Discovery and naming The cu ...
'', ''
Meyerasaurus ''Meyerasaurus'' is an extinct genus of rhomaleosaurid plesiosaur known from the Early Jurassic of Holzmaden, Baden-Württemberg in southwestern Germany. Discovery Between Holzmaden and Zell unter Aichelberg, a chalkstone and shale quarry was ...
'' and ''Rhomaleosaurus''.


Phylogeny

Smith & Dyke, 2008 redescribed the skull of ''R. cramptoni'' after its final preparation. Both Rhomaleosauridae and Pliosauridae were found to be monophyletic, and the relations between ''Rhomaleosauruss species were tested. The
cladogram A cladogram (from Greek language, Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an Phylogenetic tree, evolutionary tree because it does not s ...
below follows Smith & Dyke (2008), with the asterisk noting species removed from ''Rhomaleosaurus'' to their own genera since their study.


Paleobiology

''Rhomaleosaurus'' may have been able to pick up scents while submerged by forcing water through passages in its skull containing sensory organs. This adaptation would have enabled it to hunt its prey in a similar manner to some modern
shark Sharks are a group of elasmobranch cartilaginous fish characterized by a ribless endoskeleton, dermal denticles, five to seven gill slits on each side, and pectoral fins that are not fused to the head. Modern sharks are classified within the ...
species.


See also

*
List of plesiosaur genera This list of plesiosaurs is a comprehensive listing of all genera that have ever been included in the order Plesiosauria, excluding purely vernacular terms. The list includes all commonly accepted genera, but also genera that are now considered inv ...
*
Timeline of plesiosaur research This timeline of plesiosaur research is a chronologically ordered list of important fossil discoveries, controversies of interpretation, Taxonomy (biology), taxonomic revisions, and cultural portrayals of plesiosaurs, an order of marine reptiles ...


References

{{Portal bar, Paleontology, United Kingdom Sauropterygian genera Early Jurassic plesiosaurs of Europe Fossil taxa described in 1874 Rhomaleosauridae Taxa named by Harry Seeley