D “Dark Ages”: 3 da Vinci, Leonardo: 3 Davis, Darrell: 1 Decapoda. _See_ Coleoidea. deer: 106 Del Mar College: 27 dendrites: 14 _Dendrograptus_: 86 Denver, Colorado: 19 _Derbya_: 57 Devonian— derivation and pronunciation: 34 fossils: 41 placoderms: 87, 88 _Psilophyton_: 48 of El Paso and Van Horn regions, Llano and Marathon uplifts: 41 Diablo Mountains: 41 diatoms: 44, 46, 47 Dibranchiata. _See_ Coleoidea. _Dictyoclostus_: 55 _Dimetrodon_: 92 _Dinobastis_: 102, 103 Dinocerata: 102 dinocerates: 102, 105 dinosaurs: 89, 90-_94_, 95, 96, 97, 98, 99, 100 armored: 90, 97, 99, 100 duck-billed: 90, 97, 99 flying: 91, 94, 95 horned: 90, 99, 100 plate-bearing: 90, 97, 99 swimming: 91, 93, 95 _Diplodocus_: 90 _Diplograptus_: 86 dire wolf: 102, 103 _diris, Canis_: 102, 103 distillation: 10 _Distorsio_: 63 division, plant: 44 Dixon, J. W., Jr.: 2, 90, 91 dolomite: 11 dolphins: 95 _domestica, Canis_: 22 DuBar, Jules: 1 _Dufrenoyia_: 77 E Eastland County: 20 East Texas State College: 27 Echinodermata: 80-84 echinoderms: 80-84 asteroids: 82, 83 blastoids: 81 crinoids: 81, 82, 83 cystoids: 81, 82, 83 echinoids: 82, 84, 85 holothuroids: 84 sclerites: 83 Echinoidea: 82 echinoids: 26, 28, 29, 82, 84, 85 Cretaceous: 84, 85 plates: 84, 85 spines: 84, 85 Echinozoa: 82 Edentata: 100 edentates: 100, 101, 102 Edwards Plateau: 19, 36, 37, 42, 43 Egyptian desert: 3 _Elasmosaurus_: 91 elephants: 102 Eleutherozoa: 82 Ellison, Samuel P.: 1 El Paso region— Devonian of: 41 Ordovician of: 40 Precambrian of: 40 Silurian of: 40 _Endopachys_: 53 _Enoploclytia_: 79 entelodont: 101, 106 _Eohippus._ _See_ _Hyracotherium_. epoch, geologic: 33 era, geologic: 33-34 Erath County: 20 _Eryops_: 92 _Euomphalus_: 61 _Euphemites_: 62 Europe: 89 _Exogyra arietina_: 70 _laeviscula_: 70 _ponderosa_: 70 _texana_: 70