Early life found in Waukesha, WI

The Waukesha Biota, a 437-million-year-old fossil assemblage from Wisconsin, USA, provides a rare glimpse into life in an ancient lagoon. In his book Wonderful Life Stephen Jay Gould (1989) compared the range of form of Cambrian animals in the Burgess Shale with only five other fossil sites in the world; one of them was at Waukesha.

Spectacular new fossils from the Waukesha Biota have been revealed for the first time.

Venustulus was about 7 cm long with a semi-circular carapace, bearing appendages, a short ten-segmented body and a tail spine.

It belongs to an extinct group of arthropods (animals with an exoskeleton and jointed limbs) called synziphosurines, related to living horseshoe crabs, united with arachnids and the giant (up to 2.5 m long) extinct sea scorpions (eurypterids) in a broader group called chelicerates that have claw-like front appendages.

Reconstruction of Acheronauta stimulapis.
Acheronauta was about 6 cm long with a large carapace that covered raptorial (prey-capturing) appendages, and a long multi-segmented trunk bearing swimming appendages.

It may relate to a rare group of crustacean-like arthropods called thylacocephalans, also known from this biota.
They also occur with a mysterious unnamed arthropod known only as the ‘butterfly animal.’

Reconstruction of Parioscorpio venator.

Parioscorpio was about 5 cm long, with large raptorial appendages, like those of the living giant water bug, and a flat, oval-shaped body.
It was initially interpreted as the oldest scorpion, but is probably related to a rare group of arthropods called cheloniellids.

These ancient animals lived during the Early Silurian period, 437 million years ago.

The fossils were found in the Brandon Bridge Formation near Milwaukee, Wisconsin, in finely laminated, fine-grained mudstones, deposited in a tidal shallow marine lagoon.

A dozen types of trilobites, including some new species, and crustaceans (phyllocarids and ostracodes) are quite common.
_____
K.C. Gass & S.J. Braddy. 2023. The Waukesha Biota: A wonderful window into early Silurian life. Geology Today 39 (5): 169-175; doi: 10.1111/gto.12447
============================================
No need to hike into the Canadian Rockies when these early life forms are found in suburban Milwaukee.

​

​

​

Cool!

Thanks for the posting!

I'm sorry, the first image reminds me too much of a johnson.

LouC said:

Cool!

Thanks for the posting!

Click to expand...

The really cool thing is that I lived in Milwaukee in 1969 & went to a barbecue in Waukesha.

JacksinPA said:

The really cool thing is that I lived in Milwaukee in 1969 & went to a barbecue in Waukesha.

Click to expand...

​

A technical note summarizing the Waukesha Biota:https://gsa.confex.com/gsa/2016NC/webprogram/Paper275201.html​

THE WAUKESHA BIOTA: AN UNUSUAL GLIMPSE OF LIFE ON A SILURIAN CARBONATE PLATFORM​

WENDRUFF, Andrew J., The Ohio State University, Columbus, OH 43210, BABCOCK, Loren E., The Ohio State University, 275 Mendenhall Laboratory, 125 S. Oval Mall, Columbus, OH 43210

The Waukesha Lagerstätte in the Brandon Bridge Formation (Silurian: Llandovery, Telychian) hosts a diverse, exceptionally preserved fauna. It is among the earliest deposits of exceptional preservation following the end-Ordovician extinction. Similar to a number of other Silurian Lagerstätten in Laurentia, it was deposited on a warm, shallow-marine carbonate platform. The Waukesha Biota includes an interesting assemblage of animals and plants, some of which are characteristic of Silurian epeiric seas, others of which are expected but rare in the Silurian, and still others that could be considered “holdovers” of groups more characteristic of Cambrian Lagerstätten.

Biomineralizing animals common in the Waukesha Biota include trilobites, conulariids, and Sphenothallus (holdfasts). Echinoderms, cephalopods, brachiopods, gastropods, bivalves, bryozoans, and corals, which are normally common in Silurian shelf lithofacies, are extremely rare or unknown. Non-biomineralizing or lightly skeletized arthropods, worms, and graptolites are common. Chordates and lobopods are present.

The Waukesha Lagerstätte could be considered as providing a skewed view of biodiversity in the Silurian. However, its existence was the result of specific taphonomic processes related to localized and unusual depositional conditions. Many of the taxa in this biota are represented by similar organisms in other less well-known Silurian Lagerstätten. Instead of a skewed view, the Waukesha Biota provides evidence of what was likely the true diversity found in Silurian shallow shelf environments of Laurentia.

JacksinPA said:

​

A technical note summarizing the Waukesha Biota:https://gsa.confex.com/gsa/2016NC/webprogram/Paper275201.html​

THE WAUKESHA BIOTA: AN UNUSUAL GLIMPSE OF LIFE ON A SILURIAN CARBONATE PLATFORM​

WENDRUFF, Andrew J., The Ohio State University, Columbus, OH 43210, BABCOCK, Loren E., The Ohio State University, 275 Mendenhall Laboratory, 125 S. Oval Mall, Columbus, OH 43210

The Waukesha Lagerstätte in the Brandon Bridge Formation (Silurian: Llandovery, Telychian) hosts a diverse, exceptionally preserved fauna. It is among the earliest deposits of exceptional preservation following the end-Ordovician extinction. Similar to a number of other Silurian Lagerstätten in Laurentia, it was deposited on a warm, shallow-marine carbonate platform. The Waukesha Biota includes an interesting assemblage of animals and plants, some of which are characteristic of Silurian epeiric seas, others of which are expected but rare in the Silurian, and still others that could be considered “holdovers” of groups more characteristic of Cambrian Lagerstätten.

Biomineralizing animals common in the Waukesha Biota include trilobites, conulariids, and Sphenothallus (holdfasts). Echinoderms, cephalopods, brachiopods, gastropods, bivalves, bryozoans, and corals, which are normally common in Silurian shelf lithofacies, are extremely rare or unknown. Non-biomineralizing or lightly skeletized arthropods, worms, and graptolites are common. Chordates and lobopods are present.

The Waukesha Lagerstätte could be considered as providing a skewed view of biodiversity in the Silurian. However, its existence was the result of specific taphonomic processes related to localized and unusual depositional conditions. Many of the taxa in this biota are represented by similar organisms in other less well-known Silurian Lagerstätten. Instead of a skewed view, the Waukesha Biota provides evidence of what was likely the true diversity found in Silurian shallow shelf environments of Laurentia.

Click to expand...

Most of the Waukesha Biota fossils were found at a quarry in Waukesha County, Wisconsin, owned and operated by the Waukesha Lime and Stone Company. Other fossils were collected from a quarry in Franklin, Milwaukee County, owned and operated by Franklin Aggregate Inc. That quarry lies 32 km (20 mi) south of the quarry in Waukesha. The Franklin fossils were from blasted material apparently originating from a horizon and setting equivalent to that of the Waukesha site. Its biota is similar to that from the Waukesha site, except that it lacks trilobites.[3]

I think you need permission to hunt for fossils in either location, perhaps also pay a fee.

Taphonomy​