Diminutive Mazon Creek Horseshoe Crab with Preserved Telson

Description: The Mazon Creek deposits of the region near Braidwood, Illinois rival the other famous Lagerstatten of the Burgess Shale, Solnhofen, and Liaoning for the variety of detailed life preserved. Many exquisitely-preserved specimens are found in the ironstone nodules that make up the deposits. Xiphosura (horseshoe crabs) are related to the extinct Eurypterids, and more distantly to spiders and scorpions. They trace their ancestry back to the Cambrian, and proceed into the modern day as the genus Limulus. This one is found in the Mazon Creek deposits of Illinois, and is known as Euproops danae. This specimen is most unusual in that the telson (tail spine)I s preserved with the body within a single nodule. It is common for the telson (tail) to not be preserved, but that is not the case here. While I have had several over the past 10 years, this one is by far the smallest.