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Due to the continuing corona virus situation, this meeting will be held online through Zoom.




Dr. Scott Evans

Agouron Postdoctoral fellow, Virginia Tech

 Sunday, December 11, 2022              2:00 P.M.


Note: This is the second Sunday of December, not our usual third Sunday of the month, so as not to interfere with members’ holiday’s plans

The oldest fossils of macroscopic, complex community forming organisms, including putative animals, belong to the Ediacara Biota. These largely soft-bodied forms predate the Cambrian explosion and include representatives of the three major body plans (Porifera, Cnidaria and Bilateria) found in animals today.

            Over their approximately 40-million-year existence, three distinct faunal assemblages are recognized amongst this biota – the Avalon (~575-560 Ma), White Sea (560-550 Ma) and Nama (560-538 Ma) – named for characteristic fossil localities from each interval. Many studies have attempted to determine the drivers of the evolutionary events that led to such forms, but few have tackled the question of what happened to the Ediacara Biota – most of which did not survive into the Cambrian. In a recent study, we compiled a global database of Ediacaran fossil occurrences to test hypothesized drivers of changing diversity, specifically targeting an apparent extinction between the White Sea and Nama assemblages. We find that 80% of White Sea genera disappear from the fossil record prior to the establishment of the Nama assemblage, a loss of taxa comparable to that experienced during the ‘Big 5’ mass extinctions of the Phanerozoic. Although there are differences in paleogeographic distribution, environments sampled and mode of fossilization between all three Ediacaran assemblages, these do not match changes in diversity. This indicates that the observed decline in generic richness is not due to taphonomic or sampling bias, but instead represents a true extinction event.

            A broad range of ecologies are impacted during this time, inconsistent with biotic replacement and matching the predicted effects of major environmental change. Taxa whose morphology suggests a maximization of surface area relative to volume, a potential indicator of greater tolerance for low oxygen conditions, preferentially survive into the Nama assemblage. This is consistent with geochemical proxies demonstrating highly variable redox conditions in Neoproterozoic and Cambrian oceans, suggesting that the White Sea-Nama extinction was caused by reduced global oxygen availability. Thus, as with the ‘Big 5’ mass extinctions in Earth history, this early event in the evolution of animals appears to have been caused by climate variability.     





These are the meeting dates of the New York Paleontological Society for the 2022-2023 season. We normally meet at 2:00 P.M. in a room at the American Museum of Natural History in New York City (79th Street and Central Park West). However, due to the continuing covid-19 pandemic, the Museum is unable to assign any rooms for meetings for any groups through November. Exactly when the Museum will allow groups like our Society to reserve rooms is uncertain. It will depend on the status of covid and the relevant Museum and government policies pertaining to indoor meetings and our Society’s own judgement as to whether attendance will be safe for our members and attendees.

            But, since room availability may change, it has been decided to hold online meetings on the regular dates and times so that the schedule remains the same whether the meeting is in a room or online. One advantage of online meetings is that they will be recorded so members who can’t attend at the meeting time can view the whole meeting afterwards at their convenience. 

            Our Annual Party would normally be held at the NYU Tandon School of Engineering in Brooklyn, but, it may be unlikely that the University will allow us to meet in the event space there due to covid guidelines and the large number of people that usually attend. Due to the nature of the party (many tables, events, talks and wonderful food), this event cannot be held online.

As of this writing, all of the dates this year are on the third Sunday of the month, except April’s & December’s. Also, our Annual Holidays Party would be held if possible on a Saturday (the date to be determined), but, again, the covid crisis may likely effect this event. The dates are as follows:

September 18, 2022
December 3 or 10, 2022*
March 19, 2023
October 16, 2022
January 15,  2023
April 16, 2023
November 20, 2022
February 19, 2023
May 21, 2023

NOTE: All the above dates (for online or in-room meetings) are third Sundays of their respective months, except the April date which is the second Sunday.

            * Our Annual Party (a Saturday) - venue and date to be determined if possible.




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