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Million years ago - Wikipedia
Million years ago, abbreviated as Mya, Myr (megayear) or Ma (megaannum), is a unit of time equal to 1,000,000 years (i.e. 1×10 years), or approximately 31.6 teraseconds. 展开
Myr is in common use in fields such as Earth science and cosmology. Myr is also used with Mya or Ma. Together they make a reference system, one to a quantity, the other to a particular point in a year numbering system that … 展开
In geology, a debate remains open concerning the use of Myr (duration) plus Ma (million years ago) versus using only the term Ma. In either … 展开
• Billion years ago
• Kyr
• Megaannum (Ma)
• Symbols y and yr 展开CC-BY-SA 许可证中的维基百科文本 Mya (unit) - Simple English Wikipedia, the free encyclopedia
Million years ago - Wikiwand
Mya (unit) - Paleontology Wiki | Fandom
Mya (unit) - Wikipedia
Mya (unit) - Wikiwand
Year - Wikipedia
In the Julian calendar, the average (mean) length of a year is 365.25 days. In a non-leap year, there are 365 days, in a leap year there are 366 days. A leap year occurs every fourth year during which a leap day is intercalated into the month …
Mya (unit) - Academic Dictionaries and Encyclopedias
Miocene - Simple English Wikipedia, the free encyclopedia
Lower Triassic - Simple English Wikipedia, the free encyclopedia