CENTENNIAL HONORS COLLEGE
Western Illinois University
Undergraduate Research Day 2016
PosterPresentation
ClamShrimp(Spinicaudata)fromtheUpperTriassicLakeCinizaBeds,NewMexico
JacobShaw
FacultyMentor:ThomasHegna
Geology
The subject of this study is a fauna of clam shrimp from Triassic-aged rocks in New Mexico. They are
from the Triassic Ciniza Lake Beds (Chinle Formation) exposed near Fort Wingate, New Mexico. Clam
shrimp(Spinicaudata)areagroupofsmallcrustaceansthatliveinephemeralfreshwaterhabitats.They
arenotablefortheirbivalvecarapacethathasgrowthlinesandauniqueornamentationpattern.Clam
shrimp have a fossil record that goes back to the Devonian (̴ 350 million years ago), but their fossil
record is almost entirely composed of only their shells, with almost no data on the evolution of their
antennae,head,appendagesortail.Taxonomyoffossilclamshrimp,asaresult,isalmostentirelybased
on the patterns of ornamentation on their shells. Using this data, we can establish which groups of
knownclamshrimptheyarerelatedtoandbetterunderstandtheirevolutionintheTriassic.
In order to observe the ornamentation patterns on the clam shrimp shells, we used a SEM (Scanning
ElectronMicroscope)andhigh-resolutionmacrophotography.Inthisstudy,weclassifiedatleastthree
differentmorphotypes,eachwithitsownuniqueornamentationpattern.Thenextstageofresearchwill
trytoidentifywhichgroupofclamshrimpthesearerelated.