Thursday, May 15, 2014

An early middle Eocene Turritella


This is the third post in the continuing series of using fossil Turritella shells to "tell time." 



height 87 mm                                                                                                           




















Turritella andersoni lawsoni Dickerson, 1916

AGE RANGE: Cenozoic (early middle Eocene = 45 million years ago).

GEOGRAPHIC RANGE: Central California to northern Baja California, Mexico.

REMARKS: In order to correctly identify this species, it is necessary to have a nearly complete individual specimen that shows both the immature and mature growth stages. Note that the posterior part (immature stage) of the shell of T. andersoni lawsoni looks different that the anterior part (mature stage). A complete specimen of this subspecies reminds me of a "Tootsie Roll."

This turritellid is a subspecies, which is a group very similar to a species (in this particular case, very similar to the slightly geologically older T. andersoni Dickerson, 1916) but slightly different.


NEXT POST: A LATE EOCENE TURRITELLA

2 comments:

  1. Wonderful it’s one of my favorites. Love the pictures on all the post, they show great detail.

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