This is Mazon Monday post #82. What's your favorite Mazon Creek fossil? Tell us at email:[email protected].
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We've already looked at a few shrimp species from the Mazon Creek biota -
- Mazon Monday #13, Belotelson magister
- Mazon Monday #48, Kallidecthes richarsoni
- Mazon Monday #52, Acanthotelson stimpsoni
- Mazon Monday #64, Essoidea epiceron
- Mazon Monday #65, Paleocaris typus
Today, we are going to look at yet another... Peachocaris strongi. It was initially described in 1962 by H.K. Brooks and placed in the genus Anthracophausia. The genus was renamed to Peachocaris by Frederick Schram in 1974. Frederick Schram is an absolute giant in fossil crustaceans having written over 200 papers on the subject. He described many of the newer Mazon Creek shrimp species, including Kallidecthes, Essoidia, and more recently Lobetelson. Peachocaris is named for British paleontologist Ben Peach, who provided significant contributions to the early study of Carboniferous Malacostraca. The holo-type resides in the Yale Peabody Museum with accession number YPM 18821, which was part of the Samuel S. Strong collection. Samuel Strong was an early and prolific Mazon collector. He is mentioned in this historical document used to register the Benson (now Kodat) Farm in Morris as a historical landmark.
Other important early collectors at Mazon Creek, mentioned by Worthen, Meek and Lesquereux, were Samuel S. Strong, Michael Prendel, and John Collins, all from Morris, the largest city near the fossil beds. Lesquereux (1870, p. 476) called Strong and Even "ardent and clever investigators" (1870, p. 378), and noted that Strong had ". . . most liberally presented the State Cabinet and myself with a large number of rare and new species" of fossil plants. Strong's collection was eventually purchased by Othniel Marsh, the nineteenth-century vertebrate paleontologist of dinosaur fame, for the Peabody Museum at Yale University. It is interesting to note that, although Strong's collection was apparently rich in Mazon Creek vertebrate fossils, Marsh never described any, whereas his arch rival, Cope, the equally famous vertebrate paleontologist, described the first amphibian from that locality, which had been collected by Even. The size of Strong's collection can be appreciated from the fact that it contained nearly 1200 specimens of Acanthotelson stimpsoni, which was more than all other Mazon Creek fossil crustaceans known in other museums.
The figure at top appeared in both the "ESCONI Keys to Mazon Creek Animals" and "The Mazon Creek Fossil Fauna" by Jack Wittry, which has a more complete description.
Species similar to this animal were first found in Mississippian strata in Scotland. Due to inferior preservation of specimens in the United Kingdom and the United States, its generic name has been changed several times.
Peachocaris strongi is of moderate size. The carapace is one third the length of the animal, somewhat rectangular in outline, and has a short, sharp rostrum. A prominent optic notch protects the large eyes, which are often easily seen elevated on a stalk above the carapace. The rounded segments of the pleon decrease in size posteriorly. The prominent tail fan contains a tapered telson and uropods. All eight pairs of thoracic appendages are modified for swimming and appear blurred due to a coating of fine hairs. The pleopods are flap-like paddles. P. strongi has the body structure of a filter-feeder and often shows its last feeding in a well-preserved gut-line. This animal is usually found ghost-like and lying on its side.
P. strongi also has been turned into a catch-all name for all poorly preserved shrimp and those of small to moderate size. Though it is still the opinion of Schram that P. strongi is surely a member of the Mazon Creek Fauna, he cautions that "most of those little shrimp are generally so poorly preserved it is about 1 in 50 that can be definitively identified."
There is a mention of P. strongi in the "Richardson's Guide to the Fossil Fauna of Mazon Creek" in Chapter 12, which was written by Frederick Shram, W.D. Ian Rolfe, and Andrew A Hay.
Order Lophogastrida Peachocaris strongi (Brooks, 1962)
Figures 12.20, 12.21
Shrimplike body; rostrum moderate in size, slightly keeled, cervical groove slightly developed; eight thoracic limbs all equally developed, with segmented and setose exopods; abdominal segments equally developed, with pleural lobes all similar to each other and rounded; tailfan with broadly rounded uropods and subtriangular telson that appears to bear a set of terminal caudal furca.
This species is often confused with Anthracophausia ingelsorum, especially when poorly pre served (see comments on A. ingelsorum). This species was once placed among the "eocarids" (a catchall order) but has since been compared to, and placed among, the mysidacean types [Schram, 1986].
Specimens
