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Virtual GSA 2020

Ceara presented her MS thesis research at this virtual Annual Meeting of the Geological Society of America this year. It was nice to come together to share our science, even if virtually.

Ceara Purcell and  Alycia L. StigallHow does niche evolution contribute to diversification? A test using ecological niche modelling to examine Laurentian brachiopods during the Ordovician 

Geology Graduate Students, Faculty Participate in Annual Geological Society of American Meeting – Ohio University | College of Arts & Sciences

The Geological Society of America annual meeting is one of the largest scientific gatherings of geologists each year, and the Ohio University Geological Sciences Department historically sends a large contingent of students and faculty to showcase their research. This year the GSA meeting is online from Oct. 26-30, but departmental […]

Stigall co-organizes online conference for IGCP 653: “Zooming in on the GOBE”

Both Ceara and Alycia presented the results of their current research into Ordovician biodiversity dynamics, and Alycia co-organized the meeting.

Stigall Organizes Free Conference, Brings Together Researchers from Six Continents – Ohio University | College of Arts & Sciences

When the annual meeting of the UNESCO funded international geoscience project that she co-chairs was canceled, Dr. Alycia Stigall decided that scientific conferences are essential for building collaborations and advancing scientific knowledge, and so she found a way to host “The onset of the Great Ordovician Biodiversification Event” conference despite […]

2019-2020 Geology Department Awards

We couldn’t have an end of year departmental picnic, but Stigall Lab students still received top department awards! I’m so proud of them for all their amazing work–including Ian and Shy defending during quarantine!

I am so fortunate to work with amazing people who are also great scientists! 

Links to the university’s new articles here:
Shaolin was awarded Most Outstanding MS Student: https://www.ohio-forum.com/?p=75716

Ian was recognized as Outstanding Graduating Senior: https://www.ohio-forum.com/?p=75779

Ceara was recognized as Most Oustanding First Year MS student with the Chang Scholarship: https://www.ohio-forum.com/?p=75721

Ceara received Alumni Grant and Summer Fellowship: https://www.ohio-forum.com/?p=75726

Shaolin receives grant from Yale Peabody Museum

Congratulations to Shaolin! Shaolin received a  Schuchert and Dunbar Grants in Aid Award to fund a research trip to study the brachiopod collections at the Yale Peabody Museum. Notably, this award is named in honor of Charles Schuchert, a brachiopod worker who hailed from Ohio and produced foundational work on Ordovician brachiopods. As part of her thesis project, Shaolin will study some of Shuchert’s own specimens while investigating phylogenetic and biogeographic patterns of Ordovician brachiopods and speciation patterns during the Great Ordovician Biodiversification Event.

Ranjeev’s research on speciation in Tanzanian gastropods is published!

Ranjeev’s research on speciation in Tanzanian gastropods is published!

Congratulations to Ranjeev Epa (MS ’17)!  The research paper based on his MS thesis on systematics and morphology of Oligocene gastropods is now published in Papers in Paleontology.

Epa, Y.R., Stigall, A.L., Roberts, E.M., O’Brien, H., Stevens, N.J. 2018. Morphological diversification of ampullariid gastropods (Nsungwe Formation, late Oligocene, Rukwa Rift Basin) is coincident with onset of East African rifting. Papers in Palaeontology, 4:327-348.

Abstract:

A new freshwater gastropod fauna is described from the late Oligocene Nsungwe Formation of the Rukwa Rift Basin, Tanzania. Six new species of ampullariids are established including five species of Lanistes (L. microovum,L. nsungwensis, L. rukwaensis, L. songwellipticus and L. songweovum) and one species of Carnevalea (C. santiapillaii). These taxa occupy a morphospace region comparable to nearly half of extant Lanistes, a common and widespread genus in Africa and Madagascar. Palaeoecological evidence indicates that Nsungwe ampullariids inhabited fluvial, pond and paludal environments. Among these species are the oldest high‐spired and fluvially adapated Lanistes taxa. We suggest that Nsungwe Lanistes rapidly diversified in concert with habitat heterogeneity associated with the initiation of rifting along the western branch of the East African Rift System (EARS). Taxonomy, evolution and the biogeographical affinities of Nsungwe Formation freshwater gastropods contributes significantly to expanding the undersampled Palaeogene invertebrate fossil record of continental Africa.

 

Here is the university writeup about Ranjeev’s paper:

Paleontologists Find New Snail Species with Evolutionary Speed – Ohio University | College of Arts & Sciences

Snails may be physically rather slow, but the six new species identified by Ohio University researchers put on plenty of evolutionary speed when they had to. Ohio University paleontologists analyzing snail fossils from 24 to 26 million years ago have identified six new species-and published the first documentation of rapid …

 

Nilmani’s study of Ames Limestone Paleocommunities is published!

Nilmani’s study of Ames Limestone Paleocommunities is published!
So many beautiful brachiopods

Congratulations to Nilmani Perera (MS ’17)!  Her thesis project, which identified hierarchical biogeographic patterns in the paleo communities of the Pennsylvanian Ames Limestone has been published in Palaeogeography, Palaeoclimatology, Palaeoecology.

Perera, S.N. and Stigall, A.L. 2018. Identifying hierarchical spatial patterns within paleocommunities: An example from the Late Pennsylvanian Ames Limestone of the Appalachian basin. Palaeogeography, Palaeoclimatology, Palaeoecology, 506:1-11.

Abstract: Identifying ecological mechanisms that produce hierarchically arrayed spatial variation in community structure can be difficult in the fossil record due to conflation of spatial and temporal patterns. However, this difficulty can be mediated by minimizing the temporal duration of deposition within the unit examined. In this study, the fauna of the Upper Pennsylvanian Ames Limestone (Conemaugh Group) was analyzed to explore whether Ames paleocommunities exhibited hierarchical structure in a spatial dimension. This widespread carbonate unit was deposited during the maximum flooding interval of a glacio-eustatically influenced fifth order sea level cycle, and preserved taxa are contemporaneous within only a few thousand years. Paleocommunity structure and variability was assessed at multiple spatial scales using samples collected from seven outcrops of the Ames Limestone throughout southeastern Ohio which form a northeast to southwest trending transect parallel to the paleoshoreline. Abundance data were collected using quadrat sampling for brachiopods, bivalves, gastropods, bryozoa, corals, crinoids, echinoids, trilobites and foraminifera. Paleocommunity structure was analyzed via cluster, ordination, guild, and abundance analyses at multiple spatial scales (within a single locality, among localities and within the total study area) to provide insight on geographic partitioning of paleocommunity variation. Multiple levels of paleocommunity organization were recovered within the Ames fauna. All levels exhibited spatial partitioning, but the inferred proximate controls shifted from abiotic environmental controls at higher hierarchical levels to biotic controls at the lowest level. At the highest level, differentiation into a northern and southern regional paleocommunity was controlled primarily by substrate consistency and habitat heterogeneity related to variation in fluvial input within the basin. Local paleocommunity differentiation reflects biotic responses to topographic and environmental conditions that were geographically distributed within the region; whereas within outcrop variation was due largely to biotic feedback mechanisms.

Key points:

 

  • Paleoecology of a widespread, but temporally-restricted marine fauna was analyzed
  • Community analyses identified hierarchical constraints on spatial structure
  • Abiotic environmental controls were paramount at regional scales
  • Biotic interactions were primary at local scales
  • Hierarchical structure should be considered in paleocommunity analyses

 

Here is the university writeup about Nilmani’s paper:

Perera and Stigall Publish Study Detailing Ecological Structure of Local Fossil-Rich Limestone – Ohio University | College of Arts & Sciences

Generations of geology students at Ohio University have studied the Ames Limestone, the most fossiliferous rock layer in the Athens area, for class field trips and projects. This unit preserves skeletal remains of marine animals-corals, snails, brachiopods, trilobites, sharks- that inhabited a shallow sea that covered Athens about 300 million …

Two new publications on the Great Ordovician Biodiversification Event

Hot off the presses!  

The Stigall Lab has two new articles published in the Lethaia special issue “Contextualizing the Great Ordovician Biodiversificaiton Event”. This special issue derives from the IGCP 653 opening meeting in Durham in October 2016, and includes papers on many aspects of the GOBE and related topics.  You can access the entire issue online here.

Our lab has two contributions:

Stigall, A.L. 2018. How is biodiversity produced? Examining speciation processes during the Great Ordovician Biodiversification Event. Lethaia, 51 (2), 165-172. https://doi.org/10.1111/let.12232.

–In this paper, I make the case that it is critical to consider biological aspects of speciation, not only aggregate diversity counts, when seeking the causes of diversification events, such as the GOBE.

Trubovitz, S., & Stigall, A.L. 2018. Ecological revolution of Oklahoma’s rhynchonelliform brachiopod fauna during the Great Ordovician Biodiversification Event. Lethaia, 51(2), 277-285. https://doi.org/10.1111/let.12233.

–This is the second half of Sarah Trubovitz MS thesis, which examines community structure and body size in brachiopod communities across the GOBE in the Simpson Group of Oklahoma.

Bayesian estimation of Ordovician dispersal pathways

 

Today was an exciting day for the lab.  The paper on Ordovician dispersal pathways led by Adriane Lam which incorporates her primary MS thesis research came out. This paper is exciting for several reasons.  First, it’s always great when a student gets their research published! Second, this is the first use of bayesian biogeographic modeling with Paleozoic taxa.  Third, this project represents an evolution beyond a MS thesis project, through collaboration and improvements with additional authors at other institutions, namely Nick Matzke.  I am really so thrilled with how this paper came out.  It is a landmark is methods and has important implications for understanding Ordovician biogeography.  The only downside…Adriane titled it “Dispersal in the Ordovician” as  play on “Pirates of the Carribean” so I can’t get the Pirates theme song out of my head….

Lam, A.R., Stigall, A.L, Matzke, N.J. 2018. Dispersal in the Ordovician: Speciation patterns and paleobiogeographic analyses of brachiopods and trilobites. Palaeogeography, Palaeoclimatology, Palaeoecology, 489: 147-165. Online

Key Points:

  • Bayesian and ML methods were successfully implemented with Ordovician taxa.
  • Founder event speciation was important in the evolution of Paleozoic taxa.
  • Taxa with different larval strategies responded similarly to climate shifts.
  • Ocean currents were key influences on invertebrate dispersal patterns.
  • Results indicate most evolution within clades occurred during climate shifts.

 

Congratulations to our paleo group!

by Alycia Stigall

We had another great showing by our paleontology group at this year’s Department of Geological Sciences annual awards ceremony.

  • Outstanding graduating senior went to Emma Swaninger (Hembree lab)
  • Jenni Carnes (Hembree lab) was recognized at Outstanding TA
  • Ranjeev Epa (Stigall lab) received the Outstanding Graduate Student award
  • I was recognized for Outstanding Faculty Research and Outstanding Faculty Teaching.

It is really an honor to work these talented folks in our paleo group!