Trilobite Eggs in New York

Boulder, Colo., USA: Despite a plethora of exceptionally preserved trilobites, trilobite reproduction has remained a mystery. No previously described trilobite has had unambiguous eggs or genitalia preserved. This study by Thomas A. Hegna and colleagues reports the first occurrence of in situ preserved trilobite eggs from the Lorraine Group in upstate New York, USA.

Like other exceptionally preserved trilobites from the Lorraine Group, the complete exoskeletons are replaced with pyrite. The eggs are spherical to elliptical in shape and nearly 200 micrometers in size.

The location of the eggs is consistent with where modern female horseshoe crabs release their unfertilized eggs from the ovarian network within their head. Trilobites likely released their eggs and sperm through a genital pore of as-yet-unknown location (but probably near the posterior boundary of the head).

Because pyrite preferentially preserves the external features of fossils, there is probably a bias in the fossil record toward the preservation of arthropods that brood eggs externally. If the reproductive biology of these trilobites is representative of other trilobites, they likely spawned with external fertilization as well, which may be the ancestral mode of reproduction for early arthropods.

FEATURED ARTICLE

Pyritized in situ trilobite eggs from the Ordovician of New York (Lorraine Group): Implications for trilobite reproductive biology

Geology, http://geology.gsapubs.org/content/45/3/199.abstract

Authors: Thomas A. Hegna, ta-hegna@wiu.edu; Markus J. Martin; and Simon A.F. Darroch.

OTHER RECENTLY PUBLISHED GEOLOGY ARTICLES

A new Early Jurassic (ca. 183 Ma) fossil Lagerstätte from Ya Ha Tinda, Alberta, Canada

Rowan C. Martindale, Theodore R. Them, II, Benjamin C. Gill, Selva M. Marroquín, and Andrew H. Knoll

Open Access

http://geology.gsapubs.org/cgi/content/abstract/45/3/255



Quantifying the rise of the Himalaya orogen and implications for the South Asian monsoon

Lin Ding, R.A. Spicer, Jian Yang, Qiang Xu, Fulong Cai, Shun Li, Qingzhou Lai, Houqi Wang, T.E.V. Spicer, Yahui Yue, A. Shukla, G. Srivastava, M. Ali Khan, S. Bera, and R. Mehrotra

Open Access

http://geology.gsapubs.org/cgi/content/abstract/45/3/215



Fossil forest reveals sunspot activity in the early Permian

Ludwig Luthardt and Ronny Rößler

http://geology.gsapubs.org/cgi/content/abstract/45/3/279



Local glaciation in West Greenland linked to North Atlantic Ocean circulation during the Holocene

Avriel D. Schweinsberg, Jason P. Briner, Gifford H. Miller, Ole Bennike, and Elizabeth K. Thomas

http://geology.gsapubs.org/cgi/content/abstract/45/3/195



CO2 diffusion into pore spaces limits weathering rate of an experimental basalt landscape

Joost van Haren, Katerina Dontsova, Greg A. Barron-Gafford, Peter A. Troch, Jon Chorover, Stephen B. Delong, David D. Breshears, Travis E. Huxman, Jon D. Pelletier, Scott R. Saleska, Xubin Zeng, and Joaquin Ruiz

http://geology.gsapubs.org/cgi/content/abstract/45/3/203



Bacterial sulfur disproportionation constrains timing of Neoproterozoic oxygenation

Marcus Kunzmann, Thi Hao Bui, Peter W. Crockford, Galen P. Halverson, Clint Scott, Timothy W. Lyons, and Boswell A. Wing

http://geology.gsapubs.org/cgi/content/abstract/45/3/207



Crustal sequestration of magmatic sulfur dioxide

John Mavrogenes and Jon Blundy

http://geology.gsapubs.org/cgi/content/abstract/45/3/211



Fault-controlled dolomitization in a rift basin

Cathy Hollis, Eivind Bastesen, Adrian Boyce, Hilary Corlett, Robert Gawthorpe, Jesal Hirani, Atle Rotevatn, and Fiona Whitaker

http://geology.gsapubs.org/cgi/content/abstract/45/3/219



Location, location, location: The variable lifespan of the Laramide orogeny

Peter Copeland, Claire A. Currie, Timothy F. Lawton, and Michael A. Murphy

http://geology.gsapubs.org/cgi/content/abstract/45/3/223



Accelerating slip rates on the Puente Hills blind thrust fault system beneath metropolitan Los Angeles, California, USA

Kristian J. Bergen, John H. Shaw, Lorraine A. Leon, James F. Dolan, Thomas L. Pratt, Daniel J. Ponti, Eric Morrow, Wendy Barrera, Edward J. Rhodes, Madhav K. Murari, and Lewis A. Owen

http://geology.gsapubs.org/cgi/content/abstract/45/3/227



Equable end Mesoproterozoic climate in the absence of high CO2

Richard P. Fiorella and Nathan D. Sheldon

http://geology.gsapubs.org/cgi/content/abstract/45/3/231



Ultrafast magmatic buildup and diversification to produce continental crust during subduction

Mihai N. Ducea, George W. Bergantz, James L. Crowley, and Juan Otamendi

http://geology.gsapubs.org/cgi/content/abstract/45/3/235



A rapid lake-shallowing event terminated preservation of the Miocene Clarkia Fossil Konservat-Lagerstätte (Idaho, USA)

Huanye Wang, Qin Leng, Weiguo Liu, and Hong Yang

http://geology.gsapubs.org/cgi/content/abstract/45/3/239



What sets the size of current ripples?

Mathieu G.A. Lapotre, Michael P. Lamb, and Brandon McElroy

http://geology.gsapubs.org/cgi/content/abstract/45/3/243



The Mw 8.3 Illapel earthquake (Chile): Preseismic and postseismic activity associated with hydrated slab structures

Piero Poli, Andrei Maksymowicz Jeria, and Sergio Ruiz

http://geology.gsapubs.org/cgi/content/abstract/45/3/247



Late Quaternary glacial dynamics and sedimentation variability in the Bering Trough, Gulf of Alaska

Aleksandr Montelli, Sean P.S. Gulick, Lindsay L. Worthington, Alan Mix, Maureen Davies-Walczak, Sarah D. Zellers, and John M. Jaeger

http://geology.gsapubs.org/cgi/content/abstract/45/3/251



Flexible and responsive growth strategy of the Ediacaran skeletal Cloudina from the Nama Group, Namibia

Rachel Wood, Andrew Curtis, Amelia Penny, Andrey Yu. Zhuravlev, Shona Curtis-Walcott, Secilie Iipinge, and Frederick Bowyer

http://geology.gsapubs.org/cgi/content/abstract/45/3/259



The origin of contractional structures in extensional gneiss domes

P.F. Rey, L. Mondy, G. Duclaux, C. Teyssier, D.L. Whitney, M. Bocher, and C. Prigent

http://geology.gsapubs.org/cgi/content/abstract/45/3/263



Combining Nd isotopes in monazite and Hf isotopes in zircon to understand complex open-system processes in granitic magmas

Christopher M. Fisher, John M. Hanchar, Calvin F. Miller, Stacy Phillips, Jeffrey D. Vervoort, and Martin J. Whitehouse

http://geology.gsapubs.org/cgi/content/abstract/45/3/267



Coupling leeside grainfall to avalanche characteristics in aeolian dune dynamics

Joanna M. Nield, Giles F.S. Wiggs, Matthew C. Baddock, and Martin H.T. Hipondoka

http://geology.gsapubs.org/cgi/content/abstract/45/3/271



Temperature and volume of global marine sediments

Douglas E. LaRowe, Ewa Burwicz, Sandra Arndt, Andrew W. Dale, and Jan P. Amend

http://geology.gsapubs.org/cgi/content/abstract/45/3/275



Forecasting transitions in monogenetic eruptions using the geologic record

Gábor Kereszturi, Mark Bebbington, and Károly Németh

http://geology.gsapubs.org/cgi/content/abstract/45/3/283





GEOLOGY articles recently published ahead of print are online at http://geology.gsapubs.org/content/early/recent. All GEOLOGY articles are online http://geology.gsapubs.org/. Representatives of the media may obtain complimentary articles by contacting Kea Giles at the e-mail address above. Please discuss articles of interest with the authors before publishing stories on their work, and please make reference to GEOLOGY in articles published. Non-media requests for articles may be directed to GSA Sales and Service, gsaservice@geosociety.org.

###

http://www.geosociety.org