A black & white photo of an enrolled isoteline trilobite. The specimen is viewed from beneath, with the cephalon facing downward -- only a narrow band of the ventral cephalic doublure is exposed at the top of the image, with the median connective suture just visible. The dorsal pygidial shield is broken away, leaving an impression of the ventral doublure as a broad arcuate band with curving parallel terrace ridges. Overlapping thoracic pleurae can be seen on either side of the specimen. Underneath the missing pygidium, the hypostome -- detached from the cephalic doublure -- is revealed from the ventral side. It is of classic isoteline form, with a deep posterior embayment giving a broadly "forked" appearance. Anastomosing terrace ridges are well displayed, running more or less parallel to the lateral margins. The scale bar at the bottom of the image is 20 mm in length.
Enrolled Isotelus latus w dorsal pygidium broken away revealing classic isoteline "forked" #hypostome (ventral "mouth plate") disarticulated from cephalic doublure. Beautiful preservation of fingerprint-like #terrace ridges! #Ordovician (~450 MYA), Lindsay Fm, Colborne, #Ontario 🇨🇦 #TrilobiteTuesday