Blancan

Blancan North American Stage pada skala waktu geologi adalah zaman sekitar 4.750.000 sampai 1.808.000 juta BP.[1]

Blancan dianggap sebagai dimulainya awal-pertengahan Pliosen dan akhir dari awal Pleistosen.[2] Blancan dilanjutkan oleh Hemphillian.

Masalah Tarikh

Tanggal dimulainya Blancan masih belum sepenuhnya didirikan. Terdapat persetujuan umum bahwa tanggalnya sekitar 4.9[3] dan 4.3 juta tahun yang lalu ("mya").[4] Database GeoWhen yang sering dikutip menempatkannya pada 4.75 mya.[1]

Lebih kuat lagi ketidakcocokan mengenai akhir zaman Blancan. Sejumlah stratigrapher mengusulkan tarikh 1,808 mya yang lebih bersesuaian dengan akhir zaman Pliocene dan permulaan Pleistosen (1,808 mya). Ini juga selaras dengan tarikh kepunahah kumpulan fauna Borophagus, Hypolagus, Paenemarmota, Plesippus, Nannippus, and Rhynchotherium antara 2,2 dan 1,8 mya.[2] Ahli paleontologi lain menemukan keberlangsungan kumpulan fauna itu jauh ke dalam zaman Pleistosen, dan mengusulkan tarikh akhir 1,2 mya. Ini selaras dengan tarikh kepunahan stegomastodon dan spesies terkait serta kemunculan mammoth di bagian selatan Amerika Utara.[5]

Referensi

  1. ^ a b GeoWhen Database - Blancan. Version 1.1.0. Retrieved 2007-NOV-09.
  2. ^ a b Lundelius, E.L. Jr. et al. (1987): The North American Quaternary Sequence. In: Woodburne, Michael O. (ed.): Cenozoic mammals of North America: geochronology and biostratigraphy: 211–235. University of California Press, Berkeley. ISBN 0-520-05392-3
  3. ^ Lindsay et al. (2002)
  4. ^ Cassiliano (1999)
  5. ^ Tedford, Richard H. (1981). "Mammalian biochronology of the late Cenozoic basins of New Mexico". Geological Society of America Bulletin. 92 (12): 1008–1022. doi:10.1130/0016-7606(1981)92<1008:MBOTLC>2.0.CO;2.

Pustaka

  • Cassiliano, Michael L. (1999): Biostratigraphy of Blancan and Irvingtonian mammals in the Fish Creek–Vallecito Creek section, southern California, and a review of the Blancan-Irvingtonian boundary. J. Vertebr. Paleontol. 19(1): 169–186.
  • Feduccia, J. Alan (1970): Some birds of prey from the Upper Pliocene of Kansas. Auk 87(4): 795-797. PDF fulltext Diarsipkan 2011-06-06 di Wayback Machine.
  • Lindsay, Everett et al. (2002): Recognition of the Hemphillian/Blancan boundary in Nevada. J. Vertebr. Paleontol. 22(2): 429–442.DOI:10.1671/0272-4634(2002)022[0429:ROTHBB]2.0.CO;2 HTML abstract
  • Lourens, L. et al. (2004): The Neogene Period. In: Gradstein, F.; Ogg, J. & Smith, A.G. (eds.): A Geologic Time Scale 2004. Cambridge University Press.ISBN 0-521-78142-6
  • Lundelius, E.L. Jr. et al. (1987): The North American Quaternary Sequence. In: Woodburne, Michael O. (ed.): Cenozoic mammals of North America: geochronology and biostratigraphy: 211–235. University of California Press, Berkeley.ISBN 0-520-05392-3
  • Morgan, Gary S. & Lucas, Spencer G. (2003): Mammalian Biochronology of Blancan and Irvingtonian (Pliocene and Early Pleistocene) Faunas from New Mexico. Bulletin of the American Museum of Natural History 279: 269–320. PDF fulltext Diarsipkan 2007-07-05 di Wayback Machine.
  • Tedford, Richard H. (1981): Mammalian biochronology of the late Cenozoic basins of New Mexico. Geological Society of America Bulletin 92(12): 1008–1022.DOI:10.1130/0016-7606(1981)92<1008:MBOTLC>2.0.CO;2 HTML abstract
  • Wetmore, Alexander (1937): The Eared Grebe and other Birds from the Pliocene of Kansas. Condor 39(1): 40. PDF fulltext Diarsipkan 2008-06-25 di Wayback Machine. DjVu fulltext Diarsipkan 2011-06-06 di Wayback Machine.
  • Woodburne, Michael O. & Swisher, C.C. III (1995): Land mammal high-resolution geochronology, intercontinental overland dispersals, sea level, climate, and vicariance. Society for Economic Paleontology and Mineralogy Special Publications 54: 335–364.ISBN 1-56576-024-7

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