Paleontological Exhibit

Picture


Vogdesia (Nileus) vigilans

Ordovician Trentonian fauna
from the Galena and Maquoketa of
West De Pere and Green Bay, Wisconsin

To the second page

Local fossils (approximately 450,000,000 years old).

Click on thumbnails for full-sized photographs.

Protaxocrinus elegans A crown of this rare crinoid, from a slab containing multiple specimens. Another crown lies just above and to the right. The matrix in which Protaxocrinus occurs contains no other fossils, with the exception of one rather ragged bryozoan, but occasionally reveals ripple marks (crown: 3 cm).

Protaxocrinus elegans A complete specimen, extending from root to crown. Both positive and negative slabs were recovered. Note the prehensile "holdfast," which anchored the animal when curled around some object on the sea floor. Curiously, one "root type" holdfast was also found, among many prehensile examples, in association with Protaxocrinus (22 cm).

Protaxocrinus elegans An elaborately entwined holdfast, showing the intricacy with which this crinoid was capable of attaching itself securely. Some slabs show evidence of a fairly strong current at the time of burial, but no other individual exhibits the tenacity of this specimen (section: 4 cm).

Protaxocrinus elegans Lying among the many stems is this strange contraption which appears to be a section of stem sitting in the middle of another stem section which is split to accommodate it, much as though the whole comprised a crinoid "submarine sandwich" with one cut-open crinoid stem as "bun" and another as "ingredient." It doesn't seem to be an anal sac, as the surface shows no evidence of being porous (length: 7 cm).

Hemiarges species, a member of the trilobite order Lichida. This local specimen was identified by Neil Clark of the Hunterian Museum of Glasgow, Scotland, and Doug Boyce of the Newfoundland Geological Survey, via internet. It has been suggested that the enrolled specimen (below) may also be a Hemiarges (length: 1.5 cm).

Odontopleura parvula One of the more common species of trilobite found in the quarry near De Pere. Individuals are usually preserved upside down; this specimen was the only one found in (presumably) life orientation. Odontopleura are found in association with all other trilobite species presented on this page, occupying different levels in the same paleo environment (.9 cm).

Unidentified, enrolled trilobite Many trilobite species, when threatened, curled up in a defensive posture. This specimen, possibly also a Hemiarges (see above), was presumably aware of its impending demise. It resides next to a small crinoid crown on the same slab as the Flexicalymene senaria (below) (width: 1 cm).

Illaenus Americanus I have extracted more than a dozen complete specimens of this species of trilobite from the three Green Bay quarries. This was the first whole one I found. Each specimen has an attractive, yellow surface and is seldom found in immediate association with other fossils. Its form suggests that it was active just beneath the sea bottom, and it may have been buried below the common clutter of the sea floor (length: 3.5 cm).

Flexicalymene senaria Two specimens of this common trilobite adorn a slab covered with parts of other species, several small crinoids and brachiopods (not shown). While previous specimens on this page were collected from a quarry west of De Pere, Wisconsin, this slab comes from the Duck Creek Quarry just north of Green Bay (2.5 cm).

Calliops antevecatus Here is about as perfect a specimen of this species of trilobite as anyone can hope to find. This individual resided on a large slab with some small crinoid species and a lot of sea-floor debris. It also comes from the Duck Creek Quarry (3 c.m). My first complete trilobite of the 1997 season is a very similar species, Calyptaulax callicephalus, found on May 3 in the De Pere quarry (see the second page).

Ceraurus species A delicately etched reverse carapace of a common Ceraurus trilobite (species undetermined). The cephalon is still covered by matrix, but a single genal spine extends to the left of where the head is hidden. Five specimens of this genus, representing two species, were recovered in a three-foot radius after the "trilobite stratum" at the De Pere quarry was reexposed briefly to accommodate the building of a new exit ramp (4 cm). A more recently found specimen, of a different species of Ceraurus, is shown on the second page.

Coronocystis angulatus This represents a preliminary identification of a cystoid which is quite common in the De Pere quarry. Related to crinoids (above), cystoids lacked the multiple arms and sea-floor anchoring capabilities of their more exotic relatives. The specimen is upper center, in this picture, along with a single plate of a much larger species (lower right) and a bryozoa (left) (1.5 cm). Another cystoid, with more of its tail intact, appears on the second page.

Arthropod track About 435 million years ago, a small arthropod roused itself from the shallow sea floor and scampered off (to the right). The track is on a slab of ripple marks found in the Maquoketa formation a few miles north of Green Bay. The Maquoketa overlies the Galena in northeastern Wisconsin (track width: 2.5 cm; length: 8 cm). To see the tracks of two other arthropods, refer to the second page.

Trilobite track This is the track of a single, fairly large trilobite from the Maquoketa exposure on Edgewater Beach Road, north of Green Bay. Superimposed on the trilobite trackway are numerous and enigmatic parallel (railroad track) imprints which are the most common feature of the Maquoketa at this site. Sometimes there are just one or two such tracks, crossing a slab; often there are dozens, all running in different directions) (slab: 12 x 8 cm). Another parallel track. In this close-up, from another slab, it is noticeable that the parallel lines dig more deeply into the raised portion of the sea bottom than they do in the dips, suggesting that the responsible parties had (relatively) considerable mass. The tracks are all either straight or gently curved (as is this one); never are there sharp turns. This is about as large as they come. Even though erosion has "muddied" some of the imprints, making them sometimes appear random, a common attribute of them all is that they remain absolutely parallel throughout their entire lengths.

The Ambrosius Farm quarry near De Pere The trilobite horizons, the source of the Hemiarges, Odontopleura and Ceraurus, on this page, are easily distinguished in this picture of the De Pere quarry. Three ice fingers, at the very left, conveniently point to a deeply etched dark band that extends all the way around the quarry wall. Just below it, another band is seen, with another ice finger (just right of center) identifying it. These are the two strata in the Galena that contain the most prolific trilobite fauna and the best-preserved specimens. The bands are very thin and are separated from one another, variously, by four to ten feet. The Protaxocrinus crinoids come from lower in the quarry, in a much more consolidated, massive system, often replete with chert nodules, that nevertheless separates neatly into layers (after sufficient weathering) and weathers from a striking rust-red color to a pale gray.

This page was produced, designed and authored by C. Jeremy Shaw, in whose collection these fossils reside. Black-and-white scans are by John Foust of Syndesis Corp. from photos by the author. Color is by direct link between a video camera and "video capture" software. Permission to collect in the two quarries was kindly granted by Scott Janssen of Daanen & Janssen, Inc.

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Elsewhere (some other sites to see)

This page is presented under the auspices of the University of Wisconsin-Fox Valley.

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Jeremy Shaw
2615 East Shore Drive.
Green Bay, WI 54302