Anasazi
Anax
dragonfly — Aeshnidae > Odonata > Insecta
Anaxyrus americanus
Bufonidae > Anura > Amphibia
Anaxyrus boreas
Boreal western toad — Bufonidae > Anura > Amphibia
Anopheles stephensi
Culicidae
Antennaria glauca
Anthophora walteri
Apidae > Hymenoptera > Insecta
Antiquatonia
Apatania nigriculus
Aphelocoma coerulescens
Jay, Florida Scrub — Corvidae > Passeriformes > Aves
Aphis asclepladis
aphid —
Aphis craccivora
cowpea aphid —
Aphthargiella symphoricarpi
Arabis crandallii
Crandall Rockcress — Cruciferae
Arachis hypogaea
peanuts — Fabaceae > Fabales > Magnoliopsida
Arctia caja
garden tiger moth — Erebidae > Lepidoptera > Insecta
Arctomecon humilis
Dwarf Bear-poppy — Papaveraceae > Ranunculales > Magnoliopsida
Arenicolites
trace fossil —
Artemisia cana
silver sage — Asteraceae > Asterales > Magnoliopsida
Artemisia scopulorum
Asteraceae > Asterales > Magnoliopsida
Artimisia tridentata
sagebrush —
Asclepias verticillata
Apocynaceae > Gentianales > Magnoliopsida
Asimina longifolia
Annonaceae > Magnoliales > Magnoliopsida
Asterosoma
trace fossil —
Astragalus microcymbus
skiff milkvetch — Fabaceae > Fabales > Magnoliopsida
Astur gentilis
goshawk — Accipitridae > Accipitriformes > Aves
Asynarchus bimaculata
Asynarchus deflata
Atherix
Rhagionidae
Atoposmia abjecta
Megachilidae > Hymenoptera > Insecta
Atoposmia elongata
Megachilidae > Hymenoptera > Insecta
Atriplex confertifolia
shadscale — Amaranthaceae > Caryophyllales > Magnoliopsida
Austrostipa
Poaceae > Poales > Magnoliopsida
Azospirillum
Bacillus subtilis
Bacillaceae > Bacillales > Bacilli
Banksia spinulosa
Proteaceae > Proteales > Magnoliopsida
Bathyarchaeota
Beecheria sp.
Beedeina
Beedeina insolita
Beedeina joyitaensis
Beedeina novamexicana
Beedeina pattoni
Beedeina pristina
Beedeina socorroensis
Belted kingfisher
Belted kingfisher —
Betula alleghaniensis
Betulaceae > Fagales > Magnoliopsida
Betula lenta
Betulaceae > Fagales > Magnoliopsida
Betula popilofolia
Bidens pilosa
Asteraceae > Asterales > Magnoliopsida