Morphology and taxonomy of Paleozoic millipedes (Diplopoda: Chilognatha: Archipolypoda) from Scotland

Abstract

New millipede specimens from the Paleozoic of Scotland are described, including Archidesmus macnicoli Peach, 1882, from the Lower Devonian (Lochkovian) Tillywhandland Quarry SSSI and three new taxa—Albadesmus almondi, Pneumodesmus newmani, and Cowiedesmus eroticopodus—from the mid Silurian (late Wenlock—early Ludlow) Cowie Formation at Cowie Harbour. Cowiedesmus eroticopodus new species is placed within the new Cowiedesmidae within the new order Cowiedesmida. Kampecaris tuberculata Brade-Birks from the Lower Devonian (Siegenian) of the Lanark Basin near Dunure is shown not to be a kampecarid myriapod, redescribed as Palaeodesmus tuberculata and placed order incertae sedis within Archipolypoda. Anthracodesmus macconochiei Peach is also redescribed and tentatively placed order incertae sedis within Archipolypoda. Archidesmus macnicoli, Albadesmus almondi, and Palaeodesmus tuberculata are each demonstrated to have broad sternites with laterally placed coxal sockets and paramedian pores containing paired valves. These pores are interpreted as having housed eversible vesicles. Some specimens of Archidesmus macnicoli and Cowiedesmus eroticopodus are male and have a pair of modified legs on trunk segment 8, identified as leg pairs 10 and 11, respectively. The presence of modified anterior legs restricted to segment 8 increases the range of variability known in modified appendage location in male millipedes and compounds existing uncertainty about using the presence of gonopods on trunk segment 7 as a synapomorphy of Helminthomorpha. An affinity between Archidesmida and Cowiedesmida is suggested based on possession of modified legs on segment 8 and Archidesmida + Cowiedesmida is placed along with Euphoberiida in Archipolypoda based on possession of free, broad sternites with bivalved paramedian pores and fused pleurotergites. The oldest known evidence of spiracles is demonstrated in Pneumodesmus newmani, proving that the oldest known millipedes were fully terrestrial.

Biomechanics of octopedal locomotion: kinematic and kinetic analysis of the spiderGrammostola mollicoma

“…But evolution moved the other way round: the first multi-legged terrestrial animals presumably had eight limbs, lately radiating both towards more complex locomotor organisms (myriapods) (Wilson and Anderson, 2004) and species of larger size and with a lower number of limbs. Six-legged insects appeared later on the terrestrial surface, then vertebrates, down to quadrupeds, bipeds and even to substantially 'monopodal' species such as jumping kangaroos (Carroll, 1987).…”

Molecular and functional characterization of hemocyanin of the giant African millipede,Archispirostreptus gigas

“…subunits of S. coleoptrata are basal. This demonstrates an early divergence of distinct subunit types in the myriapods before the separation of Diplopoda and Chilopoda, which occurred at least ~420 million years ago in the Silurian period (Wilson and Anderson, 2004). Thus, the formation of the oligohexameric Hc (probably a 36-mer) is an ancient event.…”

Early Terrestrial Animals, Evolution, and Uncertainty

“…Another of the Silurian millipedes has a paired structure on the anterior part of the trunk, in the usual segmental position and with a characteristic form of a gonopod, a modified pair of legs that male millipedes use to transfer sperm to the female's genital opening (Fig. 3;Wilson and Anderson 2004). The Silurian fossils thus provide direct evidence for a similar reproductive mode as their extant relatives.…”

“…The first body fossil evidence of the animals responsible for such tracks dates from the Silurian Period (444-416 million years ago). Several millipedes have recently come to light from Stonehaven, UK (approximately 423 million years ago), including one species, Pneumodesmus newmanii, that provides the first evidence for air breathing in any form of animal (Wilson and Anderson 2004). This can be seen in spiracles (or, more biblically, stigmata)-openings into the tracheal (breathing) system which are a terrestrial feature by definition.…”

“…Shown portion of fossil 12 mm in length. After Wilson and Anderson (2004) and Coleman 1986). As a result, coal from this period is found throughout North America and Europe.…”