<sod>'''''Apatosaurus''''' (meaning "deceptive lizard") {{IPAc-en|ə|ˌ|p|æ|t|ə|ˈ|s|ɔːr|ə|s}}<ref>{{MerriamWebsterDictionary|Apatosaurus}}</ref><ref>{{Dictionary.com|Apatosaurus}}</ref>) is a [[genus]] of extinct [[sauropod]] [[dinosaur]]s that lived in North America during the [[Late Jurassic]] [[period (geology)|period]]. [[Othniel Charles Marsh]] described and named the first-known species, '''''A. ajax''''' in 1877, and a second species, '''''A. louisae''''', was discovered and named by William H. Holland in 1916. They lived about 152 to 151 million years ago (mya), during the early [[Tithonian]] age, and are now known from fossils in the [[Morrison Formation]] of modern-day [[Colorado]], [[Oklahoma]], and [[Utah]], in the United States. ''Apatosaurus'' had an average length of {{convert|22.8|m|ft|abbr=on}}, and an average mass of at least {{convert|16.4|MT|ST}}. A few specimens indicate a maximum length of 11–30% greater than average and a mass of {{convert|32.7|-|72.6|t|LT ST|abbr=on}}.<eod>
<sod>'''''Apatosaurus''''' (meaning "deceptive lizard" {{IPAc-en|ə|ˌ|p|æ|t|ə|ˈ|s|ɔːr|ə|s}}<ref>{{MerriamWebsterDictionary|Apatosaurus}}</ref><ref>{{Dictionary.com|Apatosaurus}}</ref>) is a [[genus]] of extinct [[sauropod]] [[dinosaur]]s that lived in North America during the [[Late Jurassic]] [[period (geology)|period]]. [[Othniel Charles Marsh]] described and named the first-known species, '''''A. ajax''''' in 1877, and a second species, '''''A. louisae''''', was discovered and named by William H. Holland in 1916. They lived about 152 to 151 million years ago (mya), during the early [[Tithonian]] age, and are now known from fossils in the [[Morrison Formation]] of modern-day [[Colorado]], [[Oklahoma]], and [[Utah]], in the United States. ''Apatosaurus'' had an average length of {{convert|22.8|m|ft|abbr=on}}, and an average mass of at least {{convert|16.4|MT|ST}}. A few specimens indicate a maximum length of 11–30% greater than average and a mass of {{convert|32.7|-|72.6|t|LT ST|abbr=on}}.<eod>