fossil record of camel spiders is very poor. The ca. 330 million year
old Schneidarachne saganii from Kamienna Góra in Poland (Mississipian,
Viséan) is an enigmatic fossil arachnid which seems to show some solpugid-like
features, such as large, forward-projecting chelicerae (Dunlop
& Rössler, 2003).
The oldest unquestionable camel spider is the ca. 305 million year old
Prosolpuga carbonaria from the world-famous Mazon Creek locality in
Illinois, USA (Pennsylvanian, Westphalian D) (Petrunkevitch,1913).
Even this is not particularly well preserved, but can be recognized as a
camel spider from its outline. Its incompleteness means it cannot easily be
assigned to, or compared with, any living family of Solifugae. What is
interesting is its original habitat. While living camel spiders are
predominantly associated with arid habitats or even deserts, the Coal
Measures from which Prosolpuga originates are interpreted as a rather
swampy forest environment.
The next oldest
fossils come from the ca. 115 million year old Crato Formation in
north-eastern Brazil (Cretaceous: Aptian) (Selden
& Shear, 1996;
Dunlop & Martill,
Cratosolpuga wunderlichi is now known from a number of extremely
well-preserved specimens which include details of setae, claws and even the
male flagellum. Based on these features it can be assigned with some
confidence to the modern family Ceromidae. This is particularly
significant since ceromids are restricted today to southern Africa.
What it shows, in terms of biogeography, is that ceromids must have been
present on the ancient continent of Gondwana at about the time of its
break-up during the Mesozoic, and that while they survived in the part that
became Africa they died out in the part which became South America.
Baltic amber –
which is thought to be around 40–50 million years old (Paleogene: Eocene) –
has produced a single, well-preserved fossil, Palaeoblossia groehni,
shown above (Dunlop,
Wunderlich & Poinar, 2004).
This rather small (only 5 mm long) possibly adult male example is assigned
to Daesiidae, but cannot be placed in any of the existing subfamilies. It
shows that daesiids – and Solifugae in general – were at this time present
in northern Europe, well beyond their modern range. The Baltic amber
forest is thought to have been warmer than today, but again the presence of
a camel spider was a little surprising as it was not thought to have been a
particularly arid habitat. The youngest fossil example is
Happlodontus proteus from Dominican Republic amber (Poinar
& Santiago-Blay, 1989).
The exact age of this amber is in dispute, but dates of 10–30 million years
(typically Neogene: Miocene) have been suggested. Preserving details
of the legs and cheliceral dentition, this fossil has been assigned to
Ammotrechidae. It fits neatly with the present day American
distribution of the family, which includes the Caribbean Islands.
Dunlop, J. A. & Martill, D. M. 2004. Four additional specimens of the fossil
camel spider Cratosolpuga wunderlichi Selden 1996 (Arachnida:
Solifugae) from the Lower Cretaceous Crato Formation of Brazil.
Revista Ibérica de Aracnología 9: 143-156.
Dunlop, J. A. & Rössler, R. 2003.
enigmatic, solifuge-like fossil arachnid from the Lower Carboniferous of
Kamienna Góra (Intra-Sudetic Basin), Poland. Paläontologische Zeitschrift
Dunlop, J. A., Wunderlich, J. & Poinar, G. O. 2004.
first fossil opilioacariform mite (Acari: Opilioacariformes) and the first
Baltic amber camel spider (Solifugae). Transactions of the Royal Society of
Edinburgh: Earth Sciences 94: 261-273.
Petrunkevitch, A. I. 1913. A
monograph of the terrestrial Palaeozoic Arachnida of North America.
Transactions of the Connecticut Academy of Arts and Sciences 18: 1-137.
Poinar, G. O. & Santiago-Blay, J. A. 1989. A fossil solpugid,
Happlodontus proteus, new genus, new species (Arachnida: Solifugae) from
Dominican amber. Journal of the New York Entomological Society 97: 125–132.
Selden, P. A. & Shear, W. A. 1996. The first Mesozoic Solifuge (Arachnida),
from the Cretaceous of Brazil, and a redescription of the Palaeozoic
solifuge. Palaeontology 39: 583–604.