A _Acanthoceras_: 77 _Actinomma_: 49 Africa: 87 Agnatha: 87 Alaska: 7 _Alectryonia lugubris_: 68 algae: 44, 46, 47 “algal biscuits”: 44 alligators: 95 _Allorisma_: 67 _Allosaurus_: 90, 97, 98 Allotheria: 100 allotherians: 100 Amarillo College: 27 amber: 7 amblypods: 102 _Ambocoelia_: 57 _Amelanchier_: 48 American Museum of Natural History: 2, 15, 96 ammonites: 11, 75, 76, 77, 78 Ammonoidea: 66 ammonoids: 75, 76, 77, 78 Amphibia: 89 amphibians: 87, 92 Amphineura: 56 _Amphiscapha_: 61 _Ancilla_: 64 _Angulotreta_: 55, 56 ankylosaurs: 90, 97, 99 Annelida: 78 annelids: 78 _Anomia_: 74 anteaters: 100 Anthozoa: 49, 51 _Apsotreta_: 55, 56 aragonite: 11 _Archelon_: 91 _Archetectonica_: 64 _Archaeopteryx_: 100 Archeozoic, derivation and pronunciation: 33 Archer County: 89 _Archimedes_: 54 _arietina, Exogyra_: 70 Aristotle: 3 Arizona: 7 Arkansas: 37 Arlington State College: 1, 27 armadillos: 100, 102 Aronow, Saul: 1 Arthropoda: 78, 79, 80 arthropods: 10, 78, 79, 80 crustaceans: 79, 80 insects: 7, 79 ostracodes: 79, 80 trilobites: 78, 80 Articulata: 56 Artiodactyla: 106 artiodactyls: 106 camels: 106 entelodonts: 101, 106 ash, volcanic: 5 _Astacodes_: 79 _Astartella_: 67 Asteroidea: 82 asteroids: 82, 83 Asterozoa: 82 _Astraeospongium_: 50 _Astrhelia_: 53 _Astylospongia_: 50 _Aulosteges tuberculatus_: 12, 13 Austin: 14, 17, 19, 87 Austin College: 27 Australia: 87 author, of a fossil: 22 autopores: 51 Aves: 89, 100 _Avonia_: 12, 13 _signata_: 12, 13 _subhorrida_: 12, 13