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

23 February 2017
GSA Release No. 17-05

Kea Giles, Managing Editor,
GSA Communications
+1-303-357-1057
kgiles@geosociety.org

No content found

ancient trilobites from Upstate New York

Pyritized trilobite specimens (Triarthrus eatoni) from the Ordovician Whetstone Gulf Formation (Lorraine Group), upstate New York (USA). Thomas A. Hegna et al., Geology, v. 45, p. 199-202, doi: 10.1130/G38773.1. Copyright The Geological Society of America, 2017. A larger version is available.