''Borchgrevinkium'' is an extinct

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 ...

chelicerate The subphylum Chelicerata (from Neo-Latin, , ) constitutes one of the major subdivisions of the phylum Arthropoda. Chelicerates include the sea spiders, horseshoe crabs, and arachnids (including harvestmen, scorpions, spiders, solifuges, ticks ...

arthropod Arthropods ( ) are invertebrates in the phylum Arthropoda. They possess an arthropod exoskeleton, exoskeleton with a cuticle made of chitin, often Mineralization (biology), mineralised with calcium carbonate, a body with differentiated (Metam ...

. A

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserve ...

of the single and

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 ...

, ''B. taimyrensis'', has been discovered in

deposits A deposit account is a bank account maintained by a financial institution in which a customer can deposit and withdraw money. Deposit accounts can be savings accounts, current accounts or any of several other types of accounts explained below. ...

of the Early

Devonian period The Devonian ( ) is a geologic period and system of the Paleozoic era during the Phanerozoic eon, spanning 60.3 million years from the end of the preceding Silurian period at million years ago ( Ma), to the beginning of the succeeding C ...

( Lochkovian epoch) in the

Krasnoyarsk Krai Krasnoyarsk Krai (, ) is a federal subjects of Russia, federal subject (a krai) of Russia located in Siberia. Its administrative center is the types of inhabited localities in Russia, city of Krasnoyarsk, the second-largest city in Siberia after ...

Siberia Siberia ( ; , ) is an extensive geographical region comprising all of North Asia, from the Ural Mountains in the west to the Pacific Ocean in the east. It has formed a part of the sovereign territory of Russia and its predecessor states ...

Russia Russia, or the Russian Federation, is a country spanning Eastern Europe and North Asia. It is the list of countries and dependencies by area, largest country in the world, and extends across Time in Russia, eleven time zones, sharing Borders ...

. The name of the genus honors

Carsten Borchgrevink Carsten Egeberg Borchgrevink (1 December 186421 April 1934) was a Norwegian polar explorer and a pioneer of Antarctic travel. He inspired Sir Robert Falcon Scott, Sir Ernest Shackleton, Roald Amundsen, and others associated with the Heroic Age ...

, an Anglo-Norwegian explorer who participated in many expeditions to

Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean (also known as the Antarctic Ocean), it contains the geographic South Pole. ...

. ''Borchgrevinkium'' represents a poorly known genus whose affinities are uncertain. It had several unique characteristics that differentiated it from many other arthropods, such as its long parabolic (nearly U-shaped)

prosoma The cephalothorax, also called prosoma in some groups, is a tagma of various arthropods, comprising the head and the thorax fused together, as distinct from the abdomen behind. (The terms ''prosoma'' and ''opisthosoma'' are equivalent to ''cepha ...

(head), its elongated first and second segments and the presence of paired "ridges" in the surface of its third to tenth

tergite A ''tergum'' (Latin for "the back"; : ''terga'', associated adjective tergal) is the Anatomical terms of location#Dorsal and ventral, dorsal ('upper') portion of an arthropod segment other than the head. The Anatomical terms of location#Anterior ...

s (

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 ...

halves of the segments). Furthermore, the

opisthosoma The opisthosoma is the posterior part of the body in some arthropods, behind the prosoma ( cephalothorax). It is a distinctive feature of the subphylum Chelicerata (arachnids, horseshoe crabs and others). Although it is similar in most respects ...

(the "trunk") of ''Borchgrevinkium'' was triangular, and its

telson The telson () is the hindmost division of the body of an arthropod. Depending on the definition, the telson is either considered to be the final segment (biology), segment of the arthropod body, or an additional division that is not a true segm ...

(the posteriormost division of its body), short and wedge-shaped. It was a small animal, approximately long. The only known specimen of the genus was collected in 1956 and described in 1959 by the Russian

paleontologist Paleontology, also spelled as palaeontology or palæontology, is the scientific study of the life of the past, mainly but not exclusively through the study of fossils. Paleontologists use fossils as a means to classify organisms, measure geolo ...

Nestor Ivanovich Novojilov Nestor Ivanovich Novozhilov was a Soviet paleontologist. In 1948, Novozhilov described a pliosaur specimen discovered on the banks of Russia's Volga Riveras a new species, ''Pliosaurus rossicus''. The specimen, while large, was damaged during the e ...

. He determined that it was a

eurypterid Eurypterids, often informally called sea scorpions, are a group of extinct marine arthropods that form the Order (biology), order Eurypterida. The earliest known eurypterids date to the Darriwilian stage of the Ordovician period, 467.3 Myr, mil ...

and classified it in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Mycteroptidae Mycteroptidae are a family of eurypterids, a group of extinct chelicerate arthropods commonly known as "sea scorpions". The family is one of three families contained in the superfamily Mycteropoidea (along with Hibbertopteridae and Drepanopter ...

. However, its classification changed repeatedly over the years, being transferred from Eurypterida to

Xiphosura Xiphosura (; , in reference to its sword-like telson) is an order of arthropods related to arachnids. They are more commonly known as horseshoe crabs (a name applied more specifically to the only extant family, Horseshoe crab, Limulidae). They fir ...

and back to Eurypterida some time later. ''Borchgrevinkium'' is tentatively considered as a

prosomapod Prosomapoda is a clade of euchelicerates including the groups Xiphosura (horseshoe crabs) and Planaterga (a group comprising bunodids, pseudoniscids, chasmataspidids, eurypterids and arachnids), as well as several basal synziphosurid genera. ...

, with more fossil material needed to ensure its current classification.

Description

The size of the only known specimen of ''Borchgrevinkium'', identified with the label PIN 1271/1, is estimated more or less at , making it a small

. The

was longer than wider (covering one third of the length of the animal), parabolic (nearly U-shaped) and with a length of . The

eyes An eye is a sensory organ that allows an organism to perceive visual information. It detects light and converts it into electro-chemical impulses in neurons (neurones). It is part of an organism's visual system. In higher organisms, the ey ...

are not preserved and therefore, their position or shape is unknown. The prosomal

appendages An appendage (or outgrowth) is an external body part or natural prolongation that protrudes from an organism's body such as an arm or a leg. Protrusions from single-celled bacteria and archaea are known as cell-surface appendages or surface app ...

(limbs) are only known by the tip of poorly preserved left pairs. They were short, undifferentiated and spiniferous. The

(the "trunk") was triangular and long. It was composed of 12 segments, with the first one being exceptionally long and forming with the second segment an "extension" of the prosoma. The genital appendage (a

ventral Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...

"rod" part of the

reproductive system The reproductive system of an organism, also known as the genital system, is the biological system made up of all the anatomical organs involved in sexual reproduction. Many non-living substances such as fluids, hormones, and pheromones are al ...

) of ''Borchgrevinkium'' was long, spanning from its first to its second segment. The third to tenth

s (

halves of the segments) had

distal Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position provi ...

(outwards-pointing) lobes on their sides that delimitated the dorsal and ventral parts of the opisthosoma. Furthermore, these tergites had on their surfaces converging paired "folds" or "ridges" that progressively narrowed to the center of the tenth tergite. These ridges were almost parallel to the

lateral Lateral is a geometric term of location which may also refer to: Biology and healthcare * Lateral (anatomy), a term of location meaning "towards the side" * Lateral cricoarytenoid muscle, an intrinsic muscle of the larynx * Lateral release ( ...

lobes. On the eleventh tergite, the edges were slightly curved. The pretelson (the segment that preceded the

) had a bifid (divided into two lobes) dorsal projection. The telson (the posteriormost division of the body) was cuneiform (wedge-like), short and narrow, and measured . The

ornamentation An ornament is something used for decoration. Ornament may also refer to: Decoration * Ornament (art), any purely decorative element in architecture and the decorative arts * Ornamental turning * Biological ornament, a characteristic of animals ...

of the body was composed by short

scales Scale or scales may refer to: Mathematics * Scale (descriptive set theory), an object defined on a set of points * Scale (ratio), the ratio of a linear dimension of a model to the corresponding dimension of the original * Scale factor, a number ...

with broadly rounded edges.

History of research

In 1956, the Russian

and

geologist A geologist is a scientist who studies the structure, composition, and History of Earth, history of Earth. Geologists incorporate techniques from physics, chemistry, biology, mathematics, and geography to perform research in the Field research, ...

Vladimir Vasilyevich Menner discovered a series of

s in

Devonian The Devonian ( ) is a period (geology), geologic period and system (stratigraphy), system of the Paleozoic era (geology), era during the Phanerozoic eon (geology), eon, spanning 60.3 million years from the end of the preceding Silurian per ...

near the Imangda River at the southwest of the

Taymyr Peninsula The Taymyr Peninsula ( ) is a peninsula in the Far North of Russia, in the Siberian Federal District, that forms the northernmost part of the mainland of Eurasia. Administratively it is part of the Krasnoyarsk Krai Federal subject of Russia. Ge ...

, near

Norilsk Norilsk ( rus, Нори́льск, p=nɐˈrʲilʲsk) is a closed city in Krasnoyarsk Krai, Russia, located south of the western Taymyr Peninsula, around 90 km east of the Yenisei, Yenisey River and 1,500 km north of Krasnoyarsk. Norilsk is 300 ...

, in the

(

, then the

Soviet Union The Union of Soviet Socialist Republics. (USSR), commonly known as the Soviet Union, was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 until Dissolution of the Soviet ...

). He sent them to the Russian paleontologist

, who in 1959 described, among others, a specimen labelled as PIN 1271/1, which was nearly complete. It was deposited in the

Paleontological Institute of the Russian Academy of Sciences The Paleontological Institute, Russian Academy of Sciences (PIN; ) in Moscow is among a paleontological institute. An affiliate of the Russian Academy of Sciences, it includes collections from all over the former Soviet Union, as well as from other ...

, in

Moscow Moscow is the Capital city, capital and List of cities and towns in Russia by population, largest city of Russia, standing on the Moskva (river), Moskva River in Central Russia. It has a population estimated at over 13 million residents with ...

, where it remains. Novojilov considered it unique enough to be erected as a new

, ''Borchgrevinkium'', named after the Anglo-Norwegian explorer

for his expeditions to

. He compared it with the then

xiphosura Xiphosura (; , in reference to its sword-like telson) is an order of arthropods related to arachnids. They are more commonly known as horseshoe crabs (a name applied more specifically to the only extant family, Horseshoe crab, Limulidae). They fir ...

n genus ''

Weinbergina ''Weinbergina'' is a genus of synziphosurine, a paraphyletic group of fossil chelicerate arthropods. Fossils of the single and type species, ''W. opitzi'', have been discovered in deposits of the Devonian period in the Hunsrück Slate, Germany ...

'', assuming that ''Borchgrevinkium'' was also a xiphosuran. However, the Norwegian paleontologist

Leif Størmer Leif Størmer (1 July 1905 – 15 May 1979) was a Norway, Norwegian paleontologist and geologist. He was professor of historical geology at the University of Oslo from 1946 to 1975. His father was the mathematician Carl Størmer, and his son the ...

, who assisted him during his study, noticed that what Novojilov had considered to be an accidental fissure was actually part of the "macrosegment" (the first segment), finding as well the tip of the appendages after closer examination. The presence of this macrosegment convinced Novojilov that ''Borchgrevinkium'' represented a new

, and he classified it as such. In 1966, the American paleontologist Erik Norman Kjellesvig-Waering, during a study on the

families Family (from ) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictability, structure, and safety as ...

and genera of the superfamily Stylonuracea (now known as

Stylonuroidea Stylonuroidea is an extinct superfamily of eurypterids, an extinct group of chelicerate arthropods commonly known as "sea scorpions". It is one of four superfamilies classified as part of the suborder Stylonurina. Stylonuroidea, which lived from ...

), tentatively recorded an Upper

Silurian The Silurian ( ) is a geologic period and system spanning 23.5 million years from the end of the Ordovician Period, at million years ago ( Mya), to the beginning of the Devonian Period, Mya. The Silurian is the third and shortest period of t ...

occurrence of the genus ''Borchgrevinkium'' apart from the Lower Devonian one, believing that a new specimen had been found. This specimen was later named as "''Borchgrevinkium'' sp.". In 2017, the British geologist and

paleobiologist Paleobiology (or palaeobiology) is an interdisciplinary field that combines the methods and findings found in both the earth sciences and the life sciences. An investigator in this field is known as a paleobiologist. Paleobiology is closely rel ...

James C. Lamsdell and the Irish palaeontologist

Derek Briggs Derek Ernest Gilmor Briggs (born 10 January 1950) is an Irish palaeontologist and taphonomist based at Yale University. Briggs is one of three palaeontologists, along with Harry Blackmore Whittington and Simon Conway Morris, who were key in ...

found that this specimen was YPM IP 300790, collected in the

Bertie Formation The Bertie Group or Bertie Limestone, also referred to as the Bertie Dolomite and the Bertie Formation, is an Silurian, upper Silurian (Pridoli epoch, Pridoli, or Cayugan) geologic Group (stratigraphy), group and Lagerstätte in southern Ontario, ...

in the state of

New York New York most commonly refers to: * New York (state), a state in the northeastern United States * New York City, the most populous city in the United States, located in the state of New York New York may also refer to: Places United Kingdom * ...

in 1967 by Samuel J. Ciurca, Jr., who identified it as a new undescribed species of ''Borchgrevinkium'' after contacting Størmer. Nevertheless, since this specimen was misidentified, it was redescribed as a new species of the

chasmataspidid Chasmataspidids, sometime referred to as chasmataspids, are a group of extinct chelicerate arthropods that form the Order (biology), order Chasmataspidida. Chasmataspidids are probably related to horseshoe crabs (Xiphosura) and/or sea scorpions (E ...

'' Diploaspis'', ''D. praecursor'', by Lamsdell and Briggs. The history of ''Borchgrevinkium'' soon became turbulent, being classified as a xiphosuran in 1989, and back to Eurypterida years later. ''Borchgrevinkium'' was tentatively moved by Lamsdell in 2013 to the

clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...

(

taxonomic 280px, Generalized scheme of taxonomy Taxonomy is a practice and science concerned with classification or categorization. Typically, there are two parts to it: the development of an underlying scheme of classes (a taxonomy) and the allocation ...

group)

Prosomapoda Prosomapoda is a clade of Chelicerata, euchelicerates including the groups Xiphosura (horseshoe crabs) and Planaterga (a group comprising Bunodidae, bunodids, Pseudoniscidae, pseudoniscids, Chasmataspidida, chasmataspidids, Eurypterida, eurypteri ...

Classification

Novojilov, during his description of ''Borchgrevinkium'', noted a certain resemblance to ''Weinbergina'', especially for the paired "ridges" that both have on their tergites. Based on the aforementioned macrosegment, Novojilov classified the genus as a mycteroptid eurypterid and compared it to the

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

'' Mycterops matthieui'' and '' Woodwardopterus scabrosus'' (members of the family), without finding many similarities but still classifying ''Borchgrevinkium'' in the eurypterid group. Nowadays, however, his descriptions are considered inexhaustive and based only on the best preserved material. Nevertheless, the genus continued being considered by other authors as a eurypterid. In 1966, Kjellesvig-Waering classified ''Borchgrevinkium'' with ''Woodwardopterus'' in the family Woodwardopteridae. He based this conclusion on the similarity of the ornamentation, the shape of the prosoma and the exceptional size of the first two segments of both. In 1972, Størmer questioned the affiliation of the genus in this clade and suggested that it might represent a chasmataspidid within the

order Order, ORDER or Orders may refer to: * A socio-political or established or existing order, e.g. World order, Ancien Regime, Pax Britannica * Categorization, the process in which ideas and objects are recognized, differentiated, and understood ...

Xiphosura. Following this recommendation, Victor P. Tollerton, Jr. reclassified it in 1989 inside this order during his revision of Eurypterida. In 2004, the Norwegian paleontologist Odd Erik Tetlie did not support this change and transferred ''Borchgrevinkium'' as eurypterid, again in the family Woodwardopteridae with ''Woodwardopterus'' and ''Mycterops'', but now in a different

suborder Order () is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between family and class. In biological classification, the order is a taxonomic rank used in the classification of organisms and recognized ...

, Woodwardopterina, suggesting that these arthropods actually could not represent eurypterids. The woodwardopterines were presumably united by the great elongation of the first two segments. This point of view was not approved by other researchers, and eventually Woodwardopterina was synonymized with

Stylonurina Stylonurina is one of two suborders of eurypterids, a group of extinct arthropods commonly known as "sea scorpions". Members of the suborder are collectively and informally known as "stylonurine eurypterids" or "stylonurines". They are known from ...

and Woodwardopteridae with Mycteroptidae. In addition, Lamsdell considered the genus as needing a redescription. Nowadays, ''Borchgrevinkium'' is a highly uncertain and problematic genus. Its eurypterid nature was soon denied again in 2013, when Lamsdell placed it in the clade Prosomapoda. It encompasses all

s with prosomal uniramous appendages (appendages composed of a single series of segments attached end-to-end) in the adult stage (excluding the sixth and last pair of appendages). However, the appendages of ''Borchgrevinkium'' are poorly known. Lamsdell made a note in it and in ''

Anderella ''Anderella'' is a genus of synziphosurine, a paraphyletic group of fossil chelicerate arthropods. ''Anderella'' was regarded as part of the clade Prosomapoda. Fossils of the single and type species, ''A. parva'', have been discovered in deposit ...

'', determining that in order to consolidate the classification of both genera in Prosomapoda, new fossil material is needed. A

phylogenetic In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical dat ...

analysis (the results presented in a

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) conducted by Lamsdell in 2013 on the relationships within Xiphosura and the relations to other closely related groups concluded that Xiphosura, as presently understood, was

paraphyletic Paraphyly is a taxonomic term describing a grouping that consists of the grouping's last common ancestor and some but not all of its descendant lineages. The grouping is said to be paraphyletic ''with respect to'' the excluded subgroups. In co ...

(that is, it was a group sharing a

last common ancestor A most recent common ancestor (MRCA), also known as a last common ancestor (LCA), is the most recent individual from which all organisms of a set are inferred to have descended. The most recent common ancestor of a higher taxon is generally assu ...

but not including all descendants of this ancestor) and thus not a valid phylogenetic group. Prosomapoda was erected to include several chelicerates formerly classified mostly as xiphosurans, as well as the xiphosurans themselves and

Planaterga Planaterga is a clade of prosomapod euchelicerates including several synziphosurid genera (mainly bunodids and pseudoniscids) and the group Dekatriata (which in turn includes arachnids, chasmataspidids and eurypterid Eurypterids, ofte ...

. ''Borchgrevinkium'' was not included due to its scarce known material.

Paleoecology

The only known specimen of ''Borchgrevinkium'' has been recovered in Early Devonian (

Lochkovian The Lochkovian is one of three faunal stages in the Early Devonian Epoch. It lasted from 419.2 ± 3.2 million years ago to 410.8 ± 2.8 million years ago. It marked the beginning of the Devonian Period, and was followed by the Pragian Stage. It is ...

) deposits of the Taymyr Peninsula in

, Russia. It was found alongside specimens of the chasmataspidids '' Dvulikiaspis menneri'', '' Heteroaspis stoermeri'' and '' Skrytyaspis andersoni'', as well as indeterminate eurypterids like ''

Acutiramus ''Acutiramus'' is a genus of giant predatory eurypterid, an extinct group of aquatic arthropods. Fossils of ''Acutiramus'' have been discovered in deposits of Late Silurian to Early Devonian age. Eight species have been described, five from Nor ...

''. The

lithology The lithology of a rock unit is a description of its physical characteristics visible at outcrop, in hand or core samples, or with low magnification microscopy. Physical characteristics include colour, texture, grain size, and composition. Lit ...

(physical characteristics of the

rock Rock most often refers to: * Rock (geology), a naturally occurring solid aggregate of minerals or mineraloids * Rock music, a genre of popular music Rock or Rocks may also refer to: Places United Kingdom * Rock, Caerphilly, a location in Wale ...

s) of the place has been described as dark gray

marl Marl is an earthy material rich in carbonate minerals, Clay minerals, clays, and silt. When Lithification, hardened into rock, this becomes marlstone. It is formed in marine or freshwater environments, often through the activities of algae. M ...

s with gypsiferous and dolomitic; rich in dolomite occurrences. The fossils were collected below the Early Devonian–Middle Devonian boundary.

References

{{taxonbar, from=Q85748283 Controversial taxa Early Devonian first appearances Devonian animals of Asia Devonian arthropods Fossils of Russia Fossil taxa described in 1959 Lochkovian life Prosomapoda Species known from a single specimen