This is Mazon Monday post #8. Testajapyx thomasi is the subject of this Species Spotlight, You may recognize the name of this species. It is named for ESCONI member, Tom Testa. Tom is a prolific, some might even say legendary, Mazon Creek collector. A great part of his collection resides in the Field Museum and is helping to further our knowledge of this ever interesting biota. Thanks for your invaluable contributions to science, Tom!
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Species Spotlight: Testajapyx thomasi
Testajapyx thomasi is a wingless insect. It was described in October 1987, by Jarmila Kukalova-Peck from Carleton University in Ontario, Canada.
Abstract
A new Upper Carboniferous japygid, Testajapyx thomasi n.gen. et n.sp., shows that only Diplura of Entognatha shared an ancestral ground plan with Insecta–Ectognatha. Pleuron, palps, thoracic and abdominal legs, and vesicles are compared between Diplura, Archeognatha, Monura, Thysanura, and Pterygota. The origin and evolution of side lobes on the head, thorax, and abdomen, and of cereal legs, cerci, and posttarsal (=pretarsal) claws are considered. The paleoenvironment of the earliest insects and its impact on evolution of thoracic side lobes is discussed. Consistent evidence from several biological disciplines shows that protowings evolved from thoracic side lobes, which probably originated from serial, articulated outer appendages (=exites) of the arthropodan leg. Exites were continuously active and functional and became preadapted for flapping movements. Flight developed as the pterygotes diversified. Basic wing structures are monophyletic. Flight adaptation was finished and differences in wings arose somewhat later, by various means and in parallel, in already diversified lineages of Pterygota.
That paper has some great photos and drawings.
The Acknowledgements section of the paper mentions numerous amateur paleontologists. Some are recognizable as ESCONI members.
- G. Agazzi
- Jay Herdina
- W.H. Lietz
- Larry Osterberger
- Helen Piecko
- K. and S. Ramsdell
- Thomas V. Testa
- T. and F. Wolf
Here is the text from the Creature Corner article for Testajapyx. It first appeared in November 1990.
At first glance our Creature, Testajapyx thomasi, a member of the Mazon Creek biota, appears to be a larger version of that garden pest the European earwig. Both insects display long antennae and robust ringed abdomens terminatong in fierce looking pincers. Earwigs have the archaic appearance of Tastajapyx although most earwigs possess wings that are much pleated in a radial fan-like manner. These wings p\ace them in the sub-class Pterygota, while our Creature is classed as a Dipluran in the sub-class Apterygota (wingless).
Lack of wings, entognathous mouthparts (withdrawn into the head), and caudal cerci or "pincers" are features most similar to those of the modern tropical dwelling iapygids. Recent japygids are blind denizens of moist environments, living in soil, humus, and under rocks. They are predaceous hunters of insects and other arthropodous animals, seizing prey with their jaws or grasping it with the abdominal pincers. Certain tropical Japygids grow to 4 cm. In length and are able to overcome even the largest insects. One group of japygids lack well sclerotized body parts except for the forceps and adjacent abdominal segments. This group lives with head end buried in the soil, forceps protruding to seize small prey passing by.
Testajapyx bore protruding eyes on a small rounded head. The large eyes had rounded not hexagonal facets. Its thorax consisted of three segments, each segment bearing one of the three pair of robust walking legs common to all "higher" insects; the abdomen bore vestigial legs on most segments; the last segment had the prominent terminal forceps. Thoracic limbs bore double claws, enabling the owner to climb on and up plants. The legs and terminal forceps were covered by sockets of large bristles. Bristles such as these were found on recent ground-dwelling insects, serving as a sensory warning system that stimulates the animal to jump away from any predators. Body length exclusive of the 10 mm long antennae was almost 50 mm; about twice the size of its present day look-alike, the earwig.
The previously mentioned vestigial legs or limbs appear during the embryological development of present day insects and are considered, by some experts, to be a carryover from the presumed ancestors of insects, the myriapods. While the double clawed limbs are described as the tools used by proto-insects to pull themselves up out of the water onto plant stems to escape capture.
A recurrent problem in studying fossil insects is that the earliest known forms are still very much advanced. Despite many body structures that display primitive characteristics, our creature also displays features found in the "higher" winged insects. Although both winged and wingless forms of insects were evolving explosively during the Pennsylvanian, none of the known insects of that period can truly be labeled "primitive".
Andrew A. Hay
