Fourteen oribatid mite fossils have been recovered from a terrestrial Devonian deposit near Gilboa, New York; they allow an approximate doubling of the known age of the group. Two species are represented by specimens complete enough to allow descriptions. Protochthonius gilboa n. gen. and sp. is the earliest derivative known member of the Enarthronota, and comprises the monobasic new family Protochthoniidae. Devonacarus sellnicki n. gen. and sp. also represents a monobasic new family, Devonacaridae; it may also be an early derivative enarthronote mite, but its relationships are uncertain. Two other species are represented at the site, but meaningful descriptions are not possible with available material.

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 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.

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