| 词条 | Ladd Formation | |||||||||||||||
| 释义 |
| name = Ladd Formation | image = | caption = | type = Geological formation | age = Late Cretaceous | period = Late Cretaceous | prilithology = | otherlithology = | namedfor = | namedby = | region = California | country = United States | coordinates = | unitof = | subunits = | underlies = | overlies = | thickness = | extent = | area = | map = | map_caption = }} The Ladd Formation is a Mesozoic geologic formation located in Orange County, California. PaleofaunaDinosaur remains (mainly hadrosaurid fragments) are among the fossils that have been recovered from the formation, although none have yet been referred to a specific genus.[1] In 1927 Bernard Nettleton Moore found a hadrosaur maxilla with teeth while searching for ammonites in the formation. In 1950 Marlon V. Kirk found a plesiosaur centrum (spool of the vertebra). In 1978 Robert Drachuk, also while searching for ammonites, collected a hadrosaur cranial fragment from a limestone concretion. In 1992 Robert D. Hansen found the distal tibia of a hadrosaur.[2]
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