William A. Shear

Early land animals in north america: evidence from devonian age arthropods from gilboa, new york.

A new fossil site near Gilboa, New York, is one of only three where fossils of terrestrial arthropods of Devonian age have been found. The new Gilboan fauna is younger than the other two but richer in taxa. Fragmentary remains and nearly whole specimens assigned to Eurypterida, Arachnida (Trigonotarbida, Araneae, Amblypygi, and Acari), Chilopoda [Craterostigmatomorpha(?) and Scuterigeromorpha(?)], and tentatively to Insecta (Archaeognatha) have been found. The centipedes and possible insects may represent the earliest records known for these groups.

A Devonian Spinneret: Early Evidence of Spiders and Silk Use

A nearly complete spider spinneret was found in Middle Devonian rocks (about 385 to 380 million years old) near Gilboa, New York. This is the earliest evidence yet discovered for silk production from opisthosomal spigots, and therefore for spiders. Two previously known Devonian fossils described as spiders lack any apomorphies of the order Araneae and are probably not spiders. The spigots of the Devonian spinneret resemble those of members of the living suborder Mesothelae, but the number of spigots and their distribution are like those of members of the suborder Opisthothelae, infraorder Mygalomorphae. The Devonian spider belonged to a clade that may be the sister group of all other spiders, of Mesothelae, or of Opisthothelae.

A Terrestrial Alicorhagiid Mite (Acari: Acariformes) from the Devonian of New York

Archaeacarus dubinini n. gen., n. sp., is described and illustrated based on a specimen recovered from the terrestrial fossiliferous mudstone deposits of Devonian age at Gilboa, New York. Observable character-states are consistent with its inclusion in the extant family Alicorhagiidae, one of the early-derivative taxa of the mite order Acariformes. This family record is consistent with the presence of related extant mite families in the Devonian-age Rhynie Chert of Scotland, and lends support to the validity of the latter material.

Palaeontology: An insect to fill the gap

A complete insect fossil from the Devonian period has long been sought. The finding of a candidate may improve our patchy understanding of when winged insects evolved. See Letter p.82n The early evolutionary history of the insects is obscure. Fragmentary remains of insect-like arthropods are known from the Silurian to the mid-Devonian periods, 425 million to 385 million years ago, whereas modern insects are known from the Carboniferous period, around 345 million years ago. In between lies a gap, poorly sampled by fossil specimens, during which much evolution is thought to have occurred. Here, Andre Nel and colleagues present the fossil of a complete insect that sits in that gap, about 365 million years ago in the Late Devonian. The fossil insect was terrestrial, but its features suggest that modern winged insects had already started to diversify at that early date.