This is Mazon Monday post #75. What's your favorite Mazon Creek fossil? Tell us at email:[email protected].
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Arthrolycosa antiqua, illustrated by C. E. Beecher
After posting James Alann's outstanding specimen of Arthrolycosa danielsi, I was curious and had to know a little more, so I spent some time digging... The name Arthrolycosa means "wolf spider". Specimens have been also found in the Kirov Oblast region of Russia. A. danielsi belongs to Order Araneae. Called "true spiders", they represent most, if not all, modern spiders. Wikipedia has this to say about them.
Spiders (order Araneae) are air-breathing arthropods that have eight legs, chelicerae with fangs generally able to inject venom,[2] and spinnerets that extrude silk.[3] They are the largest order of arachnids and rank seventh in total species diversity among all orders of organisms.[4] Spiders are found worldwide on every continent except for Antarctica, and have become established in nearly every habitat with the exceptions of air and sea colonization. As of August 2021, 49,623 spider species in 129 families have been recorded by taxonomists.[1] However, there has been dissension within the scientific community as to how all these families should be classified, as evidenced by the over 20 different classifications that have been proposed since 1900.[5]
Anatomically, spiders (as with all arachnids) differ from other arthropods in that the usual body segments are fused into two tagmata, the prosoma, or cephalothorax, and opisthosoma, or abdomen, and joined by a small, cylindrical pedicel (however, as there is currently neither paleontological nor embryological evidence that spiders ever had a separate thorax-like division, there exists an argument against the validity of the term cephalothorax, which means fused cephalon (head) and the thorax. Similarly, arguments can be formed against use of the term abdomen, as the opisthosoma of all spiders contains a heart and respiratory organs, organs atypical of an abdomen[6]). Unlike insects, spiders do not have antennae. In all except the most primitive group, the Mesothelae, spiders have the most centralized nervous systems of all arthropods, as all their ganglia are fused into one mass in the cephalothorax. Unlike most arthropods, spiders have no extensor muscles in their limbs and instead extend them by hydraulic pressure.
The "danielsi" in Arthrolycosa danielsi, comes from L.E. Daniels, a prolific fossil collector who lived in La Porte Indiana during the late 1800's and early 1900's. He seems to have specialized in Mazon Creek and Carboniferous insects from Kansas. He made significant contributions and there are a number of Mazon Creek animals named for him. Besides a spider, there's two insects, a cockroach, and a scorpion. What a collection! Fossilworks has references to some of the specimens he contributed to UMMP and USNM.
- Arthrolycosa danielsi (Mazon Creek spider)
- Gerarus danielsi (Mazon Creek insect)
- Asemoblatta danielsi (Mazon Creek cockroach)
- Eubleptus danielsi (Mazon Creek insect - Paleodictyioptera)
- Eoscorpius danielsi (Mazon Creek scorpion)
His collection is spoken of with great regard in turn of the century scientific proceedings. He along with J.C Carr are mentioned in the book "Early Twentieth Century Carboniferous Paleobotany in North America" on page 69 in Chapter 4 - "History of significant collections of Carboniferous (Mississippian and Pennsylvanian) plant fossils in museums in the United States".
CARR-DANIELS COLLECTION, UNIVERSITY OF ILLINOIS, URBANA, ILLINOIS
R. L. Leary
The Carr-Daniels Collection at the Natural History Museum of the University of Illinois consists almost entirely of specimens from the Mazon Creek area near Morris, Illinois. The collectors, L. E. Daniels and J. C. Carr, both resided in Morris while gathering plant fossils along Mazon Creek in Grundy County, Illinois. The majority of the specimens in these collections are ironstone nodules with only a few compressions.
The Carr-Daniels Collection was acquired by the University of Illinois in 1920. For many years the specimens remained in storage and were inaccessible for study. At one time, part of the Daniels Collection was investigated by A. C. Noé (see Chapter 14, this volume), who published photographs of several specimens (Noé, 1925). In the late 1940s, W. N. Stewart, paleobotanist of the University of Illinois, examined the Carr-Daniels Collection and prepared a catalog of the best-preserved specimens (Stewart, 1950).
As is true of all fossil plants collected from the Mazon Creek area, most specimens are foliage remains of Pecopteris and Neuropteris. Many of the leaf fragments in the Carr Daniels Collection are large enough to show something of the high degree of polymorphism within a frond. The Carr Daniels Collection also contains many fertile specimens of lycopsids, sphenopsids, and pecopterids.
Of the total number of specimens (4,018) in the two collections, 758 belong to the Daniels Collection and 3,260 to the Carr Collection. The combined collections have 103 different species assigned to 51 genera.
Back to the spider, A. danielsi was described in 1913 by A.I. Petrunkevitch in the paper "A monograph of the terrestrial Palaeozoic Arachnida of North America. Transactions of the Connecticut Acadamy of Arts and Sciences 18:1-137". Unfortunately, A danielsi is not covered in the "The Fossil Fauna of Mazon Creek" by Jack Wittry, but does appear briefly in "Richardson's Guide to the Fossil Fauna of Mazon Creek" in Chapter 11 "Archnida" on Page 147-149.
Order Araneida
The araneids (true spiders) represent another minor (2.3 percent) component of the Mazon Creek arachnids. Although poorly preserved, these specimens provide important data regarding morphological diversity of the order during the Middle Pennsylvanian.
Morphology. Prosoma ovoid to slightly hexag onal or rectangular, with up to eight ocelli variably arranged on or around an anteromedian tubercle. Foveal depression present. Ventrally, coxae radiate from large sternum.
Chelicerae with two podomeres; terminal podomeres modified as fangs. Pedipalps pedi form, with six podomeres. Remaining append ages pedal or raptorial, with seven podomeres.
Opisthosoma with 12 lightly sclerotized ter gites, and a variable, smaller number of sternites. First opisthosomal somite forms pedicle. Book lungs or tracheae on second and third opisthosomal somites. Fourth and fifth somites each with up to two pairs of spinnerets, the structures connected to the silk glands and used for spinning webs among other things (a unique trait linking the araneids). Anus terminal.
Taxonomy. All Mazon Creek araneids have segmented opisthosomata, a character state found only in the suborder Mesothelae (= Liphi stina) among extant araneids. However, none of these specimens exhibit the shared derived characters described by Plotnick and Gertsch (1976) as necessary to place them within either of the extant suborders. Because the Mazon Creek ara neids are so poorly preserved, the absence of shared derived character states in the fossil specimens may be due either to a loss of mor phology caused by taphonomic processes or to an original absence of the characters in the specimens. Because neither of these two interpretations can be rejected, the Mazon Creek araneids may be assigned either to the Mesothelae using primitive character states (segmented opisthosoma; medial, rather than terminal, spinnerets) or to Araneida incertae sedis. At the present time I favor the latter option, pending additional work to identify characters in the Mazon Creek specimens that are obligatorily correlated with the shared derived characters of the extant suborders.
The named Mazon Creek araneids are both placed in the genus Arthrolycosa (Figure 11.17). Petrunkevitch (1955) stated that this genus possessed two pairs of eyes on a median tubercle, and a carapace with convex sides.
The "poorly preserved" statement in the paragraph above must be because James Alann's specimen had yet to be found when the book was published in 1997. The specimen shown in Figure 11.17 pales in comparison to Mr. Alann's gorgeous spider.
Specimens
