Pseudogygites Latimarginatus Trilobite "Trilobutt" AReal partial trilobite fossils for sale! This piece of Ontario shale is covered in real trilobite rear segments (which we like to call "trilobutts") and other remnants of the ancient seabed. Dating back to the Middle or Upper Ordovician, these are from the species Pseudogygites Latimarginatus. This specimen was once part of the Hobberlin Museum collection and measures ~4. 25" wide. We can ship this specimen worldwide.