Xyloiuloidea is an extinct superfamily of

millipede Millipedes are a group of arthropods that are characterised by having two pairs of jointed legs on most body segments; they are known scientifically as the class Diplopoda, the name derived from this feature. Each double-legged segment is a re ...

s that existed from the

Lower Devonian The Early Devonian is the first of three epochs comprising the Devonian period, corresponding to the Lower Devonian series. It lasted from and began with the Lochkovian Stage , which was followed by the Pragian from and then by the Emsian, w ...

through the

Upper Pennsylvanian Upper may refer to: * Shoe upper or ''vamp'', the part of a shoe on the top of the foot * Stimulant, drugs which induce temporary improvements in either mental or physical function or both * ''Upper'', the original film title for the 2013 found fo ...

period in Europe and North America.

Description

Xyloiuloids are more or less cylindrical, with

sternites The sternum (pl. "sterna") is the ventral portion of a segment of an arthropod thorax or abdomen. In insects, the sterna are usually single, large sclerites, and external. However, they can sometimes be divided in two or more, in which case the ...

pleurite A sclerite (Greek , ', meaning " hard") is a hardened body part. In various branches of biology the term is applied to various structures, but not as a rule to vertebrate anatomical features such as bones and teeth. Instead it refers most commonly ...

s, and

tergites A ''tergum'' (Latin for "the back"; plural ''terga'', associated adjective tergal) is the dorsal ('upper') portion of an arthropod segment other than the head. The anterior edge is called the 'base' and posterior edge is called the 'apex' or 'mar ...

of each

body segment Segmentation in biology is the division of some animal and plant body plans into a series of repetitive segments. This article focuses on the segmentation of animal body plans, specifically using the examples of the taxa Arthropoda, Chordata, an ...

fused into a complete ring. Adults possess 40 to 50 body rings. The legs are no longer than half the height of the body. The body surface is marked by small parallel grooves (striations), which vary in surface coverage between xyloiuloid families.

Taxonomy

Xyloiuloidea comprises four families: *† Gaspestriidae *†

Nyraniidae ''Nyranius'' is a genus of fossil millipedes from the Upper Carboniferous ( Westphalian) of Europe, containing the species ''N. costulatus'' and ''N. tabulatus''. Specimens reach up to 10mm in width, and are covered in fine grooves, similar to o ...

*† Plagiascetidae *†

Xyloiulidae ''Xyloiulus'' is an extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, alt ...

The taxonomic history of Xyloiuloidea begins with

Orator F. Cook Orator Fuller Cook Jr. (May 28, 1867 – April 23, 1949) was an American botanist, entomologist, and agronomist, known for his work on cotton and rubber cultivation and for coining the term "speciation" to describe the process by which new specie ...

designating the family

in 1895. In 1969,

Richard L. Hoffman Richard Lawrence Hoffman (September 25, 1927 – June 10, 2012) was an American zoologist known as an international expert on millipedes, and a leading authority on the natural history of Virginia and the Appalachian Mountains. He was a biology ...

established the families

and Plagiascetidae, and placed all three extinct families in the extant (still-living) order

Spirobolida Spirobolida is an Order (biology), order of "round-backed" millipedes containing approximately 500 species in 12 family (biology), families. Its members are distinguished by the presence of a "pronounced Suture (anatomy), suture that runs "verti ...

, as suborder "Xyloiulidea".Hoffman, Richard L., 1969. Myriapoda, exclusive of Insecta. R572–R606. In: Moore, R.C. (Ed.), ''Treatise on Invertebrate Paleontology'', Part R, Vol. 2. Geological Society of America and University of Kansas Press, Lawrence, KS. In 2006, two new species were described and placed in the new family Gaspestriidae, and group was reassigned as a superfamily of uncertain status (''

incertae sedis ' () or ''problematica'' is a term used for a taxonomic group where its broader relationships are unknown or undefined. Alternatively, such groups are frequently referred to as "enigmatic taxa". In the system of open nomenclature, uncertain ...

'') within the

juliform Juliformia is a taxonomic superorder of millipedes containing three living orders: Julida, Spirobolida, and Spirostreptida, and the extinct group Xyloiuloidea known only from fossils. Morphology The species possess long cylindrical bodies wi ...

millipedes, a group that includes the cylindrical, fused-bodied orders Spirobolida,

Spirostreptida Spirostreptida is an order of long, cylindrical millipedes. There are approximately 1000 described species, making Spirostreptida the third largest order of millipedes after Polydesmida and Chordeumatida. Description Spirostreptida are generally ...

, and

Julida Julida is an order of millipedes. Members are mostly small and cylindrical, typically ranging from in length. Eyes may be present or absent, and in mature males of many species, the first pair of legs is modified into hook-like structures. Addi ...

References

Millipede taxonomy Arthropod superfamilies Carboniferous myriapods Devonian myriapods Carboniferous arthropods of Europe Carboniferous arthropods of North America Devonian arthropods of Europe Devonian arthropods of North America Early Devonian first appearances Pennsylvanian extinctions {{Paleo-myriapod-stub