Plate 1. Typical fossils found in the Glens Falls Limestone.
Arthropods. D.A.R. State Park rocks contain trilobites with the following imposing names: Cryptolithus tesselatus (crip-toe-LITH-us tessell-AH-tus[5]), Isotelus gigas (ice-so-TELL-us GIG-us) and Flexicalymene senaria (flex-eye-cal-ah-Mean-ee sen-AREA). These fossils are figured on [Plate 1], 1-A, B, C, D; 2; 3. Within the Park Cryptolithus tesselatus is very common wherever fossils occur. Generally only the cephalon or head portion of this trilobite is preserved. The cephalon is easily recognized by three concentric rows of pits arranged around the brim. Cryptolithus is an excellent index fossil[6] for the Park rocks. The arthropod phylum is characterized by animals with jointed legs, segmented bodies and a jointed outer armour of chitin.[7] For examples, the crabs, lobsters, spiders, scorpions and insects are arthropods. Trilobites appear early in the fossil record but they did not survive beyond the Paleozoic Era.
Explanation for [Plate 1]
(all drawings are X1 unless otherwise indicated)
1-A. Cryptolithus tesselatus, Arthropod (Trilobite), Middle Ordovician (Trenton Stage). Front view of the Cephalon or head. (X2)
1-B. Cryptolithus tesselatus, Arthropod (Trilobite), Middle Ordovician (Trenton Stage). Oblique front-lateral view of the Cephalon. (X2)
1-C. Cryptolithus tesselatus, Arthropod (Trilobite), Middle Ordovician (Trenton Stage). Top view of the Cephalon. (X2)
1-D. Cryptolithus tesselatus, Arthropod (Trilobite), Middle Ordovician (Trenton Stage). Side view of the Cephalon. (X2)
2. Isotelus gigas, Arthropod (Trilobite), Middle Ordovician. Top view of specimen.
3. Flexicalymene, Arthropod (Trilobite), Ordovician to Silurian. Top view of an enrolled specimen.
4-A. Dinorthis pectinella, Brachiopod, Middle Ordovician (Trenton Stage). Exterior view of the brachial valve.