Here is a list of dinosaurs that begin with the letter A.

1. Aardonyx
2. Abdarainurus
3. Abditosaurus
4. Abelisaurus
5. Abrictosaurus
6. Abrosaurus
7. Abydosaurus
8. Acantholipan
9. Acanthopholis
10. Achelousaurus
11. Acheroraptor
12. Achillesaurus
13. Achillobator
14. Acristavus
15. Acrocanthosaurus
16. Acrotholus
17. Adamantisaurus
18. Adasaurus
19. Adelolophus
20. Adeopapposaurus
21. Adratiklit
22. Adynomosaurus
23. Aegyptosaurus
24. Aeolosaurus
25. Aepisaurus
26. Aepyornithomimus
27. Aerosteon
28. Afromimus
29. Afrovenator
30. Agilisaurus
31. Agujaceratops
32. Agustinia
33. Ahshislepelta
34. Ajkaceratops
35. Ajnabia
36. Akainacephalus
37. Alamosaurus
38. Alaskacephale
39. Albalophosaurus
40. Albertaceratops
41. Albertadromeus
42. Albertavenator
43. Albertonykus
44. Albertosaurus
45. Albinykus
46. Alectrosaurus
47. Aletopelta
48. Algoasaurus
49. Alioramus
50. Allosaurus
51. Almas
52. Alnashetri
53. Alocodon
54. Altirhinus
55. Altispinax
56. Alvarezsaurus
57. Alwalkeria
58. Alxasaurus
59. Amanzia
60. Amargasaurus
61. Amargatitanis
62. Amazonsaurus
63. Ambopteryx
64. Ampelosaurus
65. Amphicoelias
66. Amtocephale
67. Amurosaurus
68. Amygdalodon
69. Anabisetia
70. Analong
71. Anasazisaurus
72. Anchiceratops
73. Anchiornis
74. Anchisaurus
75. Andesaurus
76. Angolatitan
77. Angulomastacator
78. Anhuilong
79. Aniksosaurus
80. Animantarx
81. Ankylosaurus
82. Anodontosaurus
83. Anomalipes
84. Anoplosaurus
85. Anserimimus
86. Antarctopelta
87. Antarctosaurus
88. Antetonitrus
89. Anzu
90. Aoniraptor
91. Aorun
92. Apatoraptor
93. Apatosaurus
94. Appalachiosaurus
95. Aquilarhinus
96. Aquilops
97. Arackar
98. Aragosaurus
99. Aralosaurus
100. Aratasaurus
101. Archaeoceratops
102. Archaeodontosaurus
103. Archaeornithoides
104. Archaeornithomimus
105. Arcovenator
106. Arcusaurus
107. Arenysaurus
108. Argentinosaurus
109. Argyrosaurus
110. Aristosuchus
111. Arkansaurus
112. Arkharavia
113. Arrhinoceratops
114. Arrudatitan
115. Arstanosaurus
116. Asfaltovenator
117. Asiaceratops
118. Asiatosaurus
119. Astrodon
120. Astrophocaudia
121. Asylosaurus
122. Atacamatitan
123. Atlantosaurus
124. Atlasaurus
125. Atlascopcosaurus
126. Atrociraptor
127. Atsinganosaurus
128. Aublysodon
129. Aucasaurus
130. Augustynolophus
131. Auroraceratops
132. Aurornis
133. Australodocus
134. Australotitan
135. Australovenator
136. Austrocheirus
137. Austroposeidon
138. Austroraptor
139. Austrosaurus
140. Avaceratops
141. Aviatyrannis
142. Avimimus