Scorpionida
Scorpions Past and Present
Biology
One of the most striking of present-day terrestrial invertebrates, getting a mention in countless b-grade horror and thriller movies, the scorpion derives its reputation from it's potent sting. The scorpion tail (or metasoma) consists of five ring-like segments and a tail-spine modified into
a sting
with venom glands. The poison sting contains a neurotoxin; 25 species are potentially lethal (5000 deaths a year from stings) Scorpions are
predators and feed on other arthropods, snakes,
lizards, and rodents. As with
arachnids, they feed only on fluids, lacking chewing mouthparts. They are long-lived (2 to 10 years, with a record of 25 years); with a gestation time 3-18 months. Mating is by indirect sperm transfer. The female gives birth to live young and cares for them.
Scorpions have a world-wide distribution, being found in deserts, grasslands, forests, intertidal zones and mountains. There are some 1100 to 1500
Recent species.
The low metabolic rate enables them to go without food for more than a year.
The average size of a scorpionid is 3 to 9 cm. The largest forms are the African genus Pandinus which reaches 18 cm, and Hadogenes troglodytes which measures 21 cm long and weighs 32 grams. Some Carboniferous scorpions are known to have
attained lengths of 44 to 86 cm or even a meter, although most of these would have been aquatic or semi-aquatic forms
Scorpionida Datasheet
note:
includes
extinct as well as living forms
Guild/Ecological niche: Aquatic, semi-aquatic, amphibious, or terrestrial medium, large, and very large
invertebrate predators
Time: Early Silurian (
Llandovery) to Present
Distribution: Worldwide
Evolved from: Mixopteracean Eurypterids
Replaced: small Eurypterids????
Descendents: Controversial - either none or Arachnida
Linnean status: Usually
Order, but
Class
has recently been proposed
Cladistic status: phylogenetic relationships still controversial
Diet / Preferred food: other
arthropods, large forms may also take small vertebrates
Evolutionary History
Scorpions bear a close relationship to Eurypterids, and there is no denying the evolutionary relationships between the two groups. Some Eurypterids, like Mixopterus, even seem to have possessed a scorpion-like poison sting. On the other hand, the scorpions - even very early ones - show evolutionary trends which are not shared by the Eurypterids, including
absence of any trace of anal valves, a primitive chelicerate character that the Eurypterida share with at least some Emeraldellids (proto-chelicerates); and distinct respiratory appendages in primitive forms, for example the long branchial filaments of the Devonian Proscorpioid Waeringoscorpio hefieri (Størmer, 1970). (Suborder Palaeoscorpinina)
But, even allowing for such evolutionary divergence, It could plausibly be suggested that the Scorpions branched off as a highly derived offshoot from small Mixopteracean eurypterid stock, some time during the early Silurian
Waeringoscorpio hefieri - ventral view, showing gills
Family ?Proscorpiidae
early Emsian epoch (Devonian)
Armorica / tropical South Euramerica (Germany)
figure from L. Della Cave & A.M. Simonetta
The first scorpions were aquatic animals, and examples with well developed gills are known from the Devonian (see above illustration).
The Protoscorpion Paleophonus , is one of a number of Silurian scorpions that are known from fossils. It lived in eastern Baltica (what is now Sweden) which at that time was colliding with Laurentia to form the continent of Euramerica. It used to be thought that these early creatures were terrestrial like modern Scorpions, but this is now known not to be the case, as they had laminate gills very like those of typical Eurypterids.
Paleophonus nuncius Thorell & Lindström, 1884
A blind aquatic, probably esturine scorpion - length about 5 cm
Family Paleophonidae
Late Silurian
Upper Högklint, Gotland, Sweden
Illustration from Fenton and Fenton The Fossil Book
During the Silurian, these creatures underwent an evolutionary radiation, so that by the early Devonian, if not earlier, all three of the major orders (here following the systematic arrangement of Dr Scott A. Stockwell) were already existing alongside each other. All of these Silurian and Devonian Scorpions were aquatic, presumably esturine, brackish, and fresh-water forms, with well developed gill fringes on the upper side of the ventral plates; the plates themselves possibly being modified opisthosomal limbs.
The early Devonian saw the first steps towards the evolution of specialized gnathobases (chewing limbs) at the bases of the first and second walking legs, which appear to have evolved as an adaptation to external digestion in a terrestrial habitat. The early true Scorpion Branchioscorpio is perhaps the first to have evolved them, though still retaining a primitive type of aquatic respiratory apparatus. This transitional genus would represent a type from which the later terrestrial scorpions evolved. It is interesting that
similar fringed, comb-like outer branched appendages characterized the gigantic Hibbertopteroid Eurypterid Cyrtoctenus.
Although scorpions and Eurypterids co-existed and evolved in parallel throughout the middle and late Paleozoic, the repeated Eurypterid tendency to gigantism and (in many forms) relatively small limbs, made it difficult for them to colonize terrestrial habitats beyond the intertidal fringe, rivers and swamps. It is likely however that some Eurypterids were every bit as terrestrial as large land crabs. Alongside the giant eurypterids there also existed giant aquatic scorpions, some reaching a meter in length (e.g. Brontoscorpio) and thus matching many of the bigger eurypterids in size. But it was the smaller Scorpions, with their relatively strong legs, that were better preadapted to a terrestrial environment. The development of a preoral chamber is a unique scorpionid development which would seem related to the acquisition of terrestrial habits. Thus it was that during the Carboniferous period the first fully terrestrial
scorpions appeared. Scorpions seem to have invaded the land as relatively large predators after a complex terrestrial ecosystem had evolved. Yet aquatic, branchiate gill-breathing scorpions still persisted right into the Jurassic period.
Relationships
Although usually grouped with the Arachnida, scorpions differ in many respects. Although
Schulz places the Scorpionida as the sister group of the Pseudoscorpiones and the Solifugae, Stockwell and other workers consider scorpions to be the "sister group" of all other arachnids (i.e. they diverged from the Arachnids when the latter were still united under a common ancestor), or even a branch of the eurypterid. Bergström considers including the Scorpions under the Class Merostomata (with Xiphosura and Eurypterids), and L. Della Cave & A.M. Simonetta point out that:
the morphologic gap between the Scorpiones and the Eurypterid. Xiphosurid stock has narrowed considerably, while the discovery of several orders of living Arachnids (Oribatid Acari, a probable Araneid, etc.) together with extinct terrestrial orders (Trigonotarbi) in the lower and middle Devonian, has correspondingly widened the gap between the Scorpions and other Arachnids, which are now known to antedate the earliest Carboniferous terrestrial Scorpions by millions of years.
While Stockwell raises the Scorpionida from the Linnean
rank of order to class, with three orders, Protoscorpiones, Palaeoscorpiones, and Scorpiones.
Such an approach represents perhaps an excessive degree of taxonomic inflation. After all, even including primitive Silurian and Devonian forms, Scorpions do not differ any more from modern forms than do, say, different groups of true spiders (Aranae) or Eurypterids, both traditionally considered orders.
It may be better practice to retain the Scorpinida as an order, but leave the class placement open for now. In view of the conflicting hypotheses, it may equally be the case that the scorpions are part of an evolutionary continuum, and it has been suggested they be placed in their own class, intermediate perhaps between Eurypterids and Arachnids
Systematics
In order to convey a more comprehensive picture, I have shown here both an earlier classification and a more recent one. In view of the lack of information regarding fossil forms (many known only
from a single, poorly preserved impression) it is ludicrous to make dogmatic statements regarding the precise evolutionary relationships of the various scorpionid lineages.
The following table presents Scorpion classification according to Dr A. Petrunkevitch's coverage in the Treatise on Invertebrate Paleontology. This table was originally complied by
Inga B. Agnér but the original web page is no longer available. I have reformatted the table but otherwise it is the same information
Dr Scott A. Stockwell has presented an alternative and much more detailed classification, which can be seen on 
this page. Dr Stockwell has also authored the Tree of Life pages on Scorpions, and
those pages contain cladograms reflecting his phylogenetic approach.
The following is a very simple summary of Dr Stockwell's arrangement, only down to Superfamily level
Order Protoscorpiones Petrunkevich, 1949 
Order Palaeoscorpiones Stockwell 1996
Superfamily Proscorpioidea Scudder, 1885
Superfamily Archaeoctonoidea Petrunkevitch, 1949
Order Scorpiones Hemprich & Ehrenberg, 1837
Suborder Mesoscorpionina Stockwell 1996
Suborder Neoscorpionina Thorell & Lindström, 1885
Infraorder
Palaeosterni Stockwell 1996
Infraorder
Orthosterni Pocock, 1911
Superfamily Buthoidea Simon, 1879
Superfamily Chactoidea Pocock, 1893
Superfamily Scorpionoidea Peters, 1862
Superfamily Vaejovoidea Thorell, 1876
Description of Living and Extinct Forms
Isobuthus rakovnicensis Fritsch
Family Isobuthidae
Although shown here in a terrestrial environment, this species was more likely to have been amphibious or even completely aquatic. It was a respectably sized scorpion, 10 cm or more in length
Because their bodies rarely fossilize, the number of known kinds of extinct scorpions is only the tiniest fraction of the number of species
which actually lived. If there are 1500 recent species, if the average species lasts for about 3 million years, and if -- as suggested by Fritsch (who described a number of Carboniferous forms in the 1900s)
-- they have since declined since their Carboniferous heyday, that would mean that the number of species that ever lived would amount, at the very least, to many hundreds of thousands. The following review therefore can give only the briefest glimpse of the past and present representatives of this group.
Suborder Protoscorpionina Petrunkevich, 1949
Dolichophonus loudonensis (Laurie, 1889)
Family Dolichophonidae
Wenlock of Scotland
image from A. Petrunkevitch, "Arachnida", Treatise on Invertebrate Paleontology
Synonym: Order Protoscorpiones Petrunkevich, 1949
time range: early Silurian to early Devonian (Llandovery to Pragian )
known distribution: Euramerica (but almost certainly worldwide)
habitat: Marginal marine and brackish, possibly also fresh water; perhaps amphibious for short periods
description: The earliest and most primitive scorpions, presumably ancestral to the other lineages. They possess
eurypterid-like legs and gills and sternocoxal arrangements, as well as well-developed lateral compound eyes. Unlike many early scorpions, Paleophonus nuntius was blind; perhaps living in murky water and hunting by smell. Other Protoscorpiones had large eyes, like their eurypterid ancestors, and hunted by sight. These first scorpions were soon replaced by the Palaeoscorpiones
phylogenetic status: Paraphyletic (ancestral to later lineages)
Included Families: the following families are listed (although with differing relationships and suborders) by Petrunkevitch: Paleophonidae, Dolichophonidae, and Palaeoscorpiidae (under Euscorpionina, i.e. not a Protoscorpione); and by Stockwell: Palaeoscorpiidae and Allopalaeophonidae
Included Genera:
Paleophonus Thorell and Lindström, 1884,
Allopalaeophonus Kjellesvig-Waering, 1986,
Dolichophonus Petrunkevitch, 1949,
Palaeoscorpius Lehmann, 1944
Webpage at the Tree of Life (still under construction): Protoscorpiones
Suborder Palaeoscorpinina Stockwell 1996
Synonym: Order Palaeoscorpiones Stockwell 1996
time range: late Silurian (Pridoli) to middle Carboniferous (Serpukhovian / Bashkirian)
known distribution: Euramerica (but almost certainly worldwide)
habitat: Marginal marine, brackish and fresh water; amphibious
description: The legs are cylindrical, like those of eurypterids and protoscorpions, but the tarsi are showing plantigrade features that could be considered land adaptations. It is likely that these
aquatic creatures were more amphibious than the protoscorpions. They also possesses an enlarged prosomal sternum that completely separates the midcoxae.
phylogenetic status: Paraphyletic (ancestral to later lineages)
Included Superfamilies: Proscorpioidea , Archaeoctonoidea
Superfamily Proscorpioidea Scudder, 1885,
Proscorpius osborni
Bertie Waterlime (Pridoli age) of New York - an esturine
predator - length about 3.5 cm
image from A. Petrunkevitch, "Arachnida", Treatise on Invertebrate Paleontology
habitat: Marginal marine, brackish, and fresh water; amphibious
description: These are completely aquatic, the gills, as in the Protoscorpiones, consisting of respiratory laminae much like those of Eurypterus, and during the Silurian probably living in typically
Eurypterid esturine environments. By the Carboniferous they had clearly found a
favorable environment in the great tropical swamps of the time. It is likely that, like other organisms of the time, they died out when climatic change and periods of drought destroyed the swamps.
time range: late Silurian (Pridoli) to middle Carboniferous (Serpukhovian / Bashkirian)
Included families:Family Proscorpiidae, Family Archaeoctonidae
Included genera:
Proscorpius Whitfield, 1885 (
Pridoli),
Archaeophonus Kjellesvig-Waering, 1986,
Waeringoscorpio Størmer, 1970 (),
Labriscorpio Leary, 1980,
Stoermeroscorpio Kjellesvig-Waering, 1986
Webpage at the Tree of Life (still under construction): Palaeoscorpiones
Superfamily Archaeoctonoidea Petrunkevitch, 1949
Archaeoctonus glaber (Peach)
Visean of Scotland - an aquatic swamp-dwelling
predator - length about 6 cm
image from A. Petrunkevitch, "Arachnida", Treatise on Invertebrate Paleontology
habitat: brackish and fresh water, amphibious
description: Like the Proscorpioidea, the Archaeoctonoidea were aquatic, mostly fresh-water forms that reached their heyday during the Middle Carboniferous. Archaeoctonus (above) was a
squat form with a broad carapace, diminutive or non-existent eyes, and short limbs. It may have hunted by smell or vibration in the murky swamp waters. Petrunkevitch includes Eoctonus in the family Archaeoctonidae, but this slender and presumably terrestrial form would seem to have little in common with Archaeoctonus.
Family Archaeoctonidae
time range: middle Carboniferous ( Visean only?)
Included genera:
Archaeoctonus Pocock, 1911; Pseudoarchaeoctonus Kjellesvig-Waering, 1986; Loboarchaeoctonus Kjellesvig-Waering, 1986
Suborder Scorpionina Hemprich & Ehrenberg, 1837
synonym: Order Scorpiones Hemprich & Ehrenberg, 1837
time range: Early Devonian to Recent
known distribution: Worldwide
habitat: Marginal marine, brackish, fresh water, semi-aquatic, to terrestrial
description: includes most known scorpions, both fossil and Recent. Primitive forms were aquatic to semi-aquatic, but more advanced forms (and all Cretaceous to recent genera and species) were and are terrestrial. All show development of an increasingly sophisticated preoral chamber comprised of the first and second leg coxae. The eyes are reduced in size, and there is a loss of one pair (and in some extinct groups, two pairs) of book-lungs, as well as a corresponding fusion of opisthosomal sternites
phylogenetic status: Monophyletic
Infraorder Mesoscorpionina Stockwell 1996
Synonym: Suborder Mesoscorpionina Stockwell 1996
time range: Visean to
Hettangian / ? Toarcian
habitat: fresh water, semi-aquatic, amphibious, or terrestrial
description: includes a diverse assemblage most known scorpions, mostly Carboniferous, although the group seems to have straggled through to the early Jurassic. Most forms were aquatic to semi-aquatic or amphibious, although a few may have been terrestrial. Eobuthus for example seems to have had typically Protoscorpion/Eurypterid gills, while Eoscorpius did not differ much in form from present scorpions, apart from the unusually long and slender legs (an adaptation for aquatic living?).
Included Families: clearly a number of families would belong in this diverse group. Included might be the Mazoniidae, Eoscorpiidae, Isobuthidae, Mesophonidae, and
others
Mazoniidae Petrunkevitch 1913
Mazonia woodiana Meek and Worthen, 1868
Mazon Creek, Illinois,
carapace shown here - 5 cm; including tail may have been 9 cm
image from A. Petrunkevitch, "Arachnida", Treatise on Invertebrate Paleontology
time range: Moscovian
habitat: fresh water
comments: includes Carboniferous Mazonia only. Mazonia would seem to be a late-persisting primitive form, in the Treatise it is included among the Protoscorpia
Included genera:
Mazonia Meek and Worthen, 1868;
Eoscorpiidae Scudder 1884
Eoscorpius carbonarius Meek and Worthen, 1868
Mazon Creek, Illinois
specimen shown here - about 6 cm
drawing from Moore, Lalicker and Fischer, Invertebrate Fossils
time range: Moscovian
habitat: amphibious or terrestrial
comments: a slender medium-sized scorpion, Eoscorpius differs from present scorpions mainly in the unusually long and slender legs.
systematic status: Petrunkevitch includes a large number of
Carboniferous genera in the family Eoscorpiidae. Stockwell divides these among
two suborders and also puts some in the incertae sedis pile. Here the family is retained for Eoscorpius only
Included genera:
Isobuthidae Petrunkevitch 1913,
time range: Moscovian
habitat: fresh water, aquatic or amphibious
comments: slender forms known only from the Carboniferous. They seem to have been mostly or completely aquatic or semi-aquatic. Eobuthus for example had typically Protoscorpion/Eurypterid gills
systematic status: Petrunkevitch gives the Isobuthidae their own superfamily
Included genera:
Mesophonidae Wills, 1910
time range: Triassic of England
habitat: terrestrial
comments: Late persisting Triassic forms. Unusual in that the stigmata of the book lings are at the posterior end of the sternites, rather than on the sternites themselves. These forms probably therefore evolved terrestrial habits independently of other scorpions. They were among the "living fossils" of their time, persisting long after most other Mesoscorpions had died out. Petrunkevitch gives the Mesophonidae their own superfamily
Included genera:
Mesophonus Wills, 1910,
Spongiophonus (
Spongiotarsus) Wills, 1947 may also belong here.
Other Mesoscorpion genera:
Heloscorpio Kjellesvig-Waering, 1986;
Phoxiscorpio Kjellesvig-Waering, 1986 (
Visean to
Hettangian / ? Toarcian);
Pareobuthus Wills, 1959;
Kronoscorpio Kjellesvig-Waering, 1986;
Paraisobuthus Kjellesvig-Waering, 1986;
Telmatoscorpio Kjellesvig-Waering, 1986.
Infraorder uncertain
Superfamily Centromachoidea Petrunkevitch 1953
Family Centromachidae Petrunkevitch 1953
time range: middle Carboniferous
comments: A single genus and species from the Carboniferous of Scotland
systematic status: given its own superfamily and family by Petrunkevitch, considered
Scorpiones incertae sedis by Stockwell
Included genus:
Centromachus Thorell and Lindström, 1885;
Superfamily Cyclophthalmoidea Petrunkevitch 1913
Family Cyclophthalmidae Petrunkevitch 1913
time range: Late Carboniferous
comments: A single genus and species from the Carboniferous of Bohemia (Czech Rep.)
systematic status: given its own superfamily and family by Petrunkevitch, considered
Scorpiones incertae sedis by Stockwell
Included genus:
Cyclophthalmus Corda, 1835;
Clade: Neoscorpionina
Synonym: Suborder Neoscorpionina Thorell & Lindström, 1885
time range: Carboniferous to Recent
known distribution: Worldwide
habitat: terrestrial
description: includes most typical scorpions, both fossil and Recent. All are terrestrial.
phylogenetic status: Monophyletic. To avoid too many subdivisions, I have not given this clade a
Linnean ranking.
Included Infraorders: Palaeosterni Stockwell 1996 , Orthosterni
Infraorder Palaeosterni Stockwell 1996
Eoctonus miniatus Petrunkevitch
Visean of Scotland - length about 1.8 cm
image from A. Petrunkevitch, "Arachnida", Treatise on Invertebrate Paleontology
Infraorder Palaeosterni Stockwell 1996
time range: Carboniferous (Bashkirian to Kasimovian)
habitat: Terrestrial
description: includes a number of forms previously included in the family Eoscorpiidae. Some, such as Eoctonus miniatus, pictured above, were tiny, while others, like the contemporary Alloscorpius granulosis, reached a respectable 10 cm in length. These creatures had long limbs, possibly rapid scrurriers. They were clearly were an important part of Carboniferous terrestrial microfauna. Note: I am here following Stockwell for no other reason than he is more recent; Petrunkevitch considers Eoctonus a member of the Archaeoctonidae
Included Families: not specified
Included genera:
Eoctonus Petrunkevitch, 1913 (
Moscovian, Mazon Creek, Illinois);
Buthiscorpius Petrunkevitch, 1953 (
Late Carboniferous, Europe);
Allobuthiscorpius Kjellesvig-Waering, 1986 (
Bashkirian to
Kasimovian);
Apiscorpio Kjellesvig-Waering, 1986;
Anthracoscorpio Kusta, 1885 (
Bashkirian to
Moscovian, England and Bohemia);
Lichnoscorpius Petrunkevitch, 1949;
Allobuthus Kjellesvig-Waering, 1986;
Coseleyscorpio Kjellesvig-Waering, 1986
Infraorder Orthosterni Pocock, 1911
time range: Carboniferous to Recent
habitat: Terrestrial
description: includes all recent scorpions
Included Superfamilies: Buthoidea Simon, 1879; Chactoidea Pocock, 1893; Scorpionoidea Peters, 1862; Vaejovoidea Thorell, 1876
Superfamily Buthoidea Simon, 1879
Family Chaerilidae Pocock, 1893
time range: no fossil record
Included genera:
Chaerilus Simon, 1877
Family Buthidae Simon, 1879
Tityus eogenus Menge
Oligocene of Europe (Baltic amber)
length of above specimen from tip of claw to curved tail, 1.2 cm
image from A. Petrunkevitch, "Arachnida", Treatise on Invertebrate Paleontology
time range: Rupelian to Recent - fossil forms known only from the Cenozoic (Oligocene Baltic amber) but clearly evolved earlier
Included genera:
Akentrobuthus Lamoral, 1976; Ananteris Thorell, 1891; Microbuthus Kraepelin, 1898; Butheolus Simon, 1883; Butheoloides Hirst, 1925; Orthochirus Karsch, 1892; Buthus Leach, 1815; Androctonus Hemprich and Ehrenberg, 1829; Leiurus Hemprich and Ehrenberg, 1829; Hemibuthus Pocock, 1900; Mesobuthus Vachon, 1950; Darchenia Vachon, 1977; Anomalobuthus Kraepelin, 1901; Apistobuthus Finnegan, 1932; Babycurus Karsch, 1886; Birulatus Vachon, 1974; Buthacus Birula, 1908; Buthiscus Biruls, 1905; Odontobuthus Vachon, 1950; Odonturus Karsch, 1879; Kraepelinia Vachon, 1974; Liobuthus Birula, 1898; Lissothus Vachon, 1948; Cicielus Vachon, 1948; Compsobuthus Vachon, 1949; Psammobuthus Birula, 1911; Hoplocystis Karsch, 1884; Hottentotta Birula, 1908; Vachoniolus Levy, Amitai & Shulov, 1973; Vachonus Tikader & Bastewade, 1983; Isometrus Hemprich & Ehrenberg, 1829; Isometroides Keyserling, 1885; Lychas Koch, 1845; Lychasoides Vachon, 1974; Pocockius Francke, 1985; Pseudolychas Kraepelin, 1912; Scorpiobuthus Werner, 1939; Charmus Karsch, 1879; Karasbergia Hewitt, 1914; Parabuthus Pocock, 1890; Uroplectes Peters, 1862; Grosphus Simon, 1880; Tityobuthus Pocock, 1893; Centruroides Marx in Howard, 1890; Rhopalurus Thorell, 1876; Tityus Koch, 1836; Mesotityus González-Sponga, 1982; Tityopsis Armas, 1974; Alayotityus Armas, 1973; Microtityus Kjellesvig-Waering, 1966; Zabius Thorell, 1894
Superfamily Chactoidea Pocock, 1893
Family Chactidae Pocock, 1893
Included genera:
Nullibrotheas Williams, 1974; Chactas Gervais in Walckenaer & Gervais, 1844; Teuthraustes Simon, 1878; Vachoniochactas González-Sponga, 1978; Chactopsis Kraepelin, 1912; Brotheas Koch, 1837; Broteochactas Pocock, 1893
Family Euscorpiidae Laurie, 1896
Included genera:
Euscorpius Thorell, 1876; Megacormus Karsch, 1881; Plesiochactas Pocock, 1900; Troglocormus Francke, 1982
Family Scorpiopsidae Kraepelin, 1899
Included genera:
Scorpiops Peters, 1862; Parascorpiops Banks, 1928; Neoscorpiops Vachon, 1980; Euscorpiops Vachon, 1980; Alloscorpiops Vachon, 1980; Dasyscorpiops Vachon, 1974
Superfamily Scorpionoidea Peters, 1862
Family Bothriuridae Simon, 1880:
Included genera:
Lisposoma Lawrence, 1928; Thestylus Simon, 1880; Phoniocercus Pocock, 1893; Tehuankea Cekalovic, 1973; Brachistosternus Pocock, 1893; Orobothriurus Maury, 1975; Bothriurus Peters, 1862; Timogenes Simon, 1880; Vachonia Abalos, 1954; Urophonius Pocock, 1893; Centromachetes Lönnberg, 1897; Cercophonius Peters, 1862
Family Ischnuridae Simon, 1879
Included genera:
Heteroscorpion Birula, 1903; Hemiscorpius Peters, 1862; Habibiella Vachon, 1974; Hadogenes Kraepelin, 1894; Chiromachetes Pocock, 1899; Cheloctonus Pocock, 1892; Opisthacanthus Peters, 1862; Chiromachus Pocock, 1893; Iomachus Pocock, 1893; Liocheles Sundevall, 1833
Family Urodacidae Pocock, 1893
Included genera:
Urodacus Peters, 1862
Family Scorpionidae Peters, 1862
time range: Rupelian to Recent - fossil forms known only from the Cenozoic (Oligocene Baltic amber) but clearly evolved earlier
Scorpio Linnaeus, 1758; Opistophthalmus Koch, 1837; Pandinus Throell, 1876; Heterometrus Hemprich and Ehrenberg, 1829
Family Diplocentridae Pocock, 1893
Included genera:
Diplocentrus Peters, 1962; Didymocentrus Kraepelin, 1905; Bioculus Stahnke, 1968; Tarsoporosus Francke, 1978; Cazierius, Francke, 1978; Oiclus Simon, 1880; Heteronebo Pocock, 1899; Nebo Kraepelin, 1898;
Superfamily Vaejovoidea Thorell, 1876
Family Vaejovidae Thorell, 1876
Included genera:
Uroctonus Thorell, 1976; Uroctonites Williams & Savary 1991; Vaejovis Koch, 1836 (Mexicanus & Granulatus species groups); Nitidulus species group; Serradigitus Stahnke, 1974; Syntropis Kraepelin, 1901; Punctipalpi Species Group; Eusthenura Species Group; Pseudouroctonus Stahnke, 1974; Paravaejovis Williams, 1980; Paruroctonus Werner, 1934; Smeringurus Haradon, 1983; Vejovoidus. Stahnke, 1974
Family Superstitionidae Stahnke, 1940
Included genera:
Superstitionia Stahnke, 1940; Troglotayosicus Lourenço, 1981;
Belisarius Simon, 1879; Alacran Francke, 1982; Sotanochactas Francke, 1986; Typhlochactas Mitchell, 1968
Family Iuridae Thorell, 1876
Included genera:
Iurus Thorell, 1876; Paraiurus Francke, 1986; Caraboctonus Pocock, 1893; Hadruroides Pocock, 1893; Hadrurus Thorell, 1876; Anuroctonus Pocock, 1893
Superfamily uncertain (incertae sedis)
Palaeopisthacanthus Petrunkevitch, 1913;
Compsoscorpius Petrunkevitch, 1949 - a small form from the
Bashkirian of England
Infraorder uncertain
Garnettius hungerfordis (Elias)
body length about 12 cm
image from A. Petrunkevitch, "Arachnida", Treatise on Invertebrate Paleontology
A large number of extinct, mostly Carboniferous forms are known from fragmentary remains and hint at a greater past diversity.
Included genera are:
Praearcturus Woodward, 1871;
Branchioscorpio Kjellesvig-Waering, 1986;
Acanthoscorpio Kjellesvig-Waering, 1986;
Gigantoscorpio Størmer, 1963;
Anthracochaerilus Kjellesvig-Waering, 1986;
Trachyscorpio Kjellesvig-Waering, 1986;
Scoloscorpio Kjellesvig-Waering, 1986;
Garnettius Petrunkevitch, 1953 (a large squat form with a rectangular carapace,
Late Carboniferous of Kansas);
Boreoscorpio Kjellesvig-Waering, 1986;
Leioscorpio Kjellesvig-Waering, 1986;
Opsieobuthus Kjellesvig-Waering, 1986;
Pseudobuthiscorpius Kjellesvig-Waering, 1986;
Petaloscorpio Kjellesvig-Waering, 1986;
Waterstonia Kjellesvig-Waering, 1986;
Stenoscorpio Kjellesvig-Waering, 1986;
Willsiscorpio Kjellesvig-Waering, 1986;
Liassiscorpionides Bode, 1951(from the Early Jurassic of Germany - one of the few known Jurassic species. The tail is short and slender);
Mioscorpio Kjellesvig-Waering, 1986
Suborder, infraorder, clade, and superfamily uncertain:
Microlabis sternbergii
A small probably aquatic form from the Moscovian of Bohemia.
The complete animal (including the tail) was probably about 4.5 cm in length
Petrunkevitch includes it under the Isobuthidae,
Stockwell considers it in Scorpionida incertae sedis
image from A. Petrunkevitch, "Arachnida", Treatise on Invertebrate Paleontology
A number of mostly Carboniferous and probably mostly aquatic forms are too poorly known to be placed in a particular family or order, and must remain for the time being incertae sedis. Included here are a few giant forms.
Included genera: Brontoscorpio Kjellesvig-Waering, 1972;
Feistmantelia Fric, 1904;
Bromsgroviscorpio Kjellesvig-Waering, 1986;
Titanoscorpio Kjellesvig-Waering, 1986;
Wattisonia Wills, 1960;
Palaeomachus Pocock, 1911 (known from only a single pedipalp -
Late Carboniferous of England);
Tiphoscorpio Kjellesvig-Waering, 1986;
Eskiscorpio Kjellesvig-Waering, 1986;
Microlabis Corda, 1839;
Hydroscorpius Kjellesvig-Waering, 1986
Websites
Scorpion Emporium - Scott A. Stockwell - best on the Web
Scorpionida - Scorpions and their extinct relatives - also by Scott A. Stockwell
Introduction to the Scorpiones - short useful intro
Scorpions (Desert USA) - useful intro
ARACHNOLOGY - SCORPIONES - very good list of
annotated links
scorpionslinks - more links
Books
Invertebrate Zoology, Robert D. Barnes, (Saunders College,
Philadelphia, 1980). Reprinted as Invertebrate Zoology by Edward E. Ruppert, Robert D. Barnes - although an excellent coverage of Invertebrates, very little on Scorpions - only listed here because I used it for a reference when writing this page
Bergström, J 1979, "Morphology of fossil arthropods as a guide to phylogenetic relationships", In Gupta, A. P. (ed.) Arthropod Phylogeny, 3-56. New York: Van Nostrand Reinhold Co. - only listed here because I referred to it in this page
Scorpion Biology and Research ed. by Philip Brownell and Gary Polis -
haven't read it, looks technical
L. Della Cave & A.M. Simonetta, "Early Paleozoic Arthropoda and problems of Arthropod phylogeny; with some notes on taxa of dubious affinities" In Simonetta and Morris, ed. 1989, The early evolution of Metazoa and the significance of problematic taxa - excellent overview of fossil arthropods, maybe a little dated now, with a brief mention of scorpion relationships
Fenton and Fenton The Fossil Book (1958, Doubleday & Co., Garden City, New York) - reprinted as The Fossil Book : A Record of Prehistoric Life by Pat Vickers Rich (Editor), Thomas Hewitt Rich, Mildred Adams Fenton, Patricia V. Rich, Carroll Lane Fenton - nice drawing of Paleophonus (reproduced on this page) in the original edition
Moore, Lalicker and Fischer, Invertebrate Fossils, 1952, McGraw-Hill Book Company, Inc., New York, Toronto, London) - brief coverage of scorpions, now out of date
Petrunkevitch, A. 1960. Arachnida. P42-P162 in Moore, R.C. (ed.) Treatise on Invertebrate Paleontology - Part P: Arthropoda 2: Chelicerata. Geological Society of America and University of Kansas Press, Lawrence, Kansas. - This is the best material in book form. Technical and now rather dated. Even so I still used Petrunkevitch as a main reference. Lots of line-drawings of extinct scorpions
(Treatise on Invertebrate Paleontology webpage
Scorpions : Everything About Purchase, Care, Feeding, and Housing (Barron's Complete Pet Owner's Manual) by Manny Rubio - Scorpions as pets
Schulz, J.W. 1990. Evolutionary morphology and phylogeny of Arachnida. Cladistics, 6:1-38.
Stockwell, S.A. 1989. Revision of the Phylogeny and Higher Classification of Scorpions (Chelicerata). Ph.D. Dissertation, University of California, Berkeley. 413 pp. - regarding which, see
Classification of the Class Scorpionida
Karl Von Zittel, Text-Book of Paleontology, ed. Charles R. Eastman, 2nd ed. vol.1 1937
Macmillan & Co. London,
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page uploaded 12 June 2002
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(originally uploaded on Kheper Site 27 April 1999)
text by
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