Publication Announcement: Smithian (Early Triassic) ammonoids from Crittenden Springs, Elko County, Nevada

Smithian (Early Triassic) ammonoids from Crittenden Springs, Elko County, Nevada: Taxonomy, biostratigraphy and biogeography by James F. Jenks and Arnaud Brayard. New Mexico Museum of Natural History & Science Bulletin, 78: 1-175. 2018.

Jenks_Brayard_CoverThis 175-page volume presents the results of decades of research at Crittenden Springs, one of the world’s most prolific Early Triassic ammonoid localities. If you are interested in ordering Bulletin 78, it costs $16 and you can contact Holly Lowe, Store Manager for the NMMNH&S, at hlowe@naturalhistoryfoundation.orgto place orders.

Abstract— We present a comprehensive monographic treatment of all currently known Smithian (Early Triassic) ammonoid taxa from Crittenden Springs. Extensive collection efforts from numerous stratigraphically discontinuous, condensed outcrops over a period spanning four decades has yielded a total of 60 taxa. This activity has also resulted in the recognition of a new biostratigraphic succession unique to Crittenden Springs, consisting of 12 ammonoid intervals that normally occur within a typical ~1 m thick condensed outcrop. Ammonoids of early Smithian age are reported for the first time from this locality. Intraspecific variation of the more abundant taxa is documented and illustrated. Early and middle Smithian ammonoid biostratigraphy is shown to correlate reasonably well with the latest early and nearly the entire middle Smithian portion of the newly reported Utah and Nevada successions as well as most Tethyan and western Panthalassic localities. Late Smithian biostratigraphy correlates well with both the Utah and Nevada successions as well as all major worldwide localities. The latest late Smithian ammonoid fauna also contains well preserved, undoubted members of the Glyptophiceras sinuatum fauna, originally reported from the Tethyan realm. At least nine taxa from Crittenden Springs (e.g., Preflorianites cf. P. radiansMesohedenstroemia kwangsiana and Wasatchites cf. W. distractus), while common to several Tethyan localities, have not yet been reported from Utah, Nevada or other western USA localities. Many of the newly described taxa further confirm the paleoequatorial nature of ammonoid faunas from Crittenden Springs as well as the low paleolatitude faunal exchange that occurred between opposite sides of the Panthalassic Ocean during Smithian time. One new family, the Crittendentidae is erected, whose composition includes Crittendenites n. gen. and Wyomingites Hyatt, 1900. Newly described taxa (three genera and six species) include a proptychitid, Gambleites eichhorni n. gen., n. sp., a galfettitid, Montelloites stephensi n. gen., n. sp., a crittendenitid, Crittendenites jattioti n. gen., n. sp., an arctoceratid, Arctoceras rubyae n. sp., a prionitid, Meekoceras bylundi n. sp. and an aspenitid, Aspenites weitschati n. sp. Additionally, two new genera  (Condensoceras n. gen. and Elkoceras n. gen.) are erected for previously described taxa, the xenoceltitid “Xenoceltites” youngi (Kummel and Steele) and family Incertae Sedis,“Dieneroceras” spathi (Kummel and Steele), respectively. Also included are seven newly reported taxa, e.g., Proharpoceras carinatitabulatumMeekoceras millardenseMeekoceras cf. M. olivieriKashmirites cf. K. guangxiense and Glyptophiceras cf. G. sinuatum.

 

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