From Large to Small to Large: Phylogenetic Systematics of Rotulid “Sand Dollars” and their Tiny Relatives
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Authors
Pimentel, Fiorella
Issue Date
2006-04-28
Type
Presentation
Language
en_US
Keywords
Alternative Title
Abstract
The Clypeasteroida (sand dollars and allies) comprises three
clades: Clypeasterina, Laganina, and Scutellina (true sand dollars).
The diverse Laganina contains taxa that vary greatly in size, from the
large, sand dollar-like rotulids to miniaturized forms like Fibulariella.
Fibulariella, though once included in the family Fibulariidae, is actually
more closely related to rotulids than fibulariids. Previous analyses
showed two separate derivations of tiny laganines lacking internal
buttresses: 1) fibulariids, and 2) Fibulariella (Mooi et al. 2001). I tested
this scenario by examining material and the literature to better
circumscribe key taxa, especially Fibulariella and its Eocene relatives,
Thagastea and Tarphypygus. A previously unrecognized group of tiny
Fibulariella-like laganines (the “Unknowns”) in the Eocene neotropics
was also included in the study. To reveal underlying processes and
driving forces behind laganine evolution, a phylogenetic analyses of
59 characters was performed using PAUP, and taxa were mapped in
time and space.
Description
1 broadside : ill.
Citation
Publisher
Kalamazoo College