Announcements from the April Chapter Meeting

The Announcements
View the full set of April announcements by clicking here. There are currently so many chapter activities, the verbal meeting announcements can only cover a portion. The calendar lists even more opportunities to get involved. Please note a date change: the Big Chapter Project at Kiest Park Conservation Area is scheduled for May 14th. Opportunities and contacts, websites, and other details are available in the announcements.

COVID-19 update: Chapter meetings are now provided in hybrid format. Masks indoors and social distancing are now “recommended, not required” at the in-person meeting at Dallas College – Brookhaven. We’re tracking with CDC guidance. If you opt to participate online, please know your extra caution is appreciated. Details here.

Highlights of the Meeting

Recognition – Congratulations to Master Naturalists achieving major milestones in the first quarter of 2022.
250 Hours – Kate Whidden, Elizabeth Wilkinson
500 Hours – Dorothy Buechel, Ginger Greatens, Mark Kennedy
1000 Hours – Jean Hill
Well done, each of you!

Our new Volunteer Spotlight featured Blanca Reyna. Blanca has volunteered extensively at Casa Guanajuato, Twelve Hills, Latinex In Translation, co-chaired the Diversity and Inclusion committee, and provided many Facebook posts. Sadly, she is moving to San Antonio soon. Thanks for your dedicated service, Blanca. We wish you the best and will miss you.

Marine Fossils of North Texas and the North Sulphur River 

A huge thank you to Mick Tune for a fascinating presentation on North Texas fossils, specifically megafossils of the late Cretaceous period. Mick is a dedicated fossil collector and student of paleontology with decades of experience in the North Sulphur River. His enthusiasm is reflected in the extensive fossil collection he had on display. He is also the author of Wildering: Anyone’s Guide to Enjoying the American Wilderness.

Mick began with an overview of conditions during the late Cretaceous period and how, 80 million years ago, the North Sulphur River area was near the edge of the Western Interior Seaway. Through the late Cretaceous and until the rise of the Rocky Mountains, this body of water covered much of Texas and ran north to the Arctic. This relatively shallow-water location led to significant accumulations of fossils in the river’s area.

Mick then discussed specific examples, demonstrating them from his North Sulphur River collection. His collection of shark and mosasaur teeth showed how durable tooth enamel has an important role in preserving the fossil record. Along with coprolites (fossilized fecal matter), teeth often provide much of the available information about ancient sharks.

Showing a number of vertebrae, Mick focused on the mosasaur, a marine reptile and apex predator. One particularly striking image was of a distinctive mosasaur bite mark into a mosasaur vertebra: the tooth had been powerfully driven well into the bone. He also showed plesiosaur fossils, another large, predatory marine reptile.

Among large bony fishes of the period, he discussed pachyrhizodus and xiphactinus. Though these predators ranged from 8 to over 18 feet long, they were also prey to mosasaurs. Mick also displayed ammonites and fossilized turtle bones, one plate having a long groove from a shark tooth. He showed several flint points, discussing how Native American artifacts can also be found in the riverbed.

Mick closed with a discussion of the recent history of the North Sulphur River and the coming Lake Ralph Hall. That this area offers such a fine fossil hunting is a byproduct of an engineering project. To alleviate flooding and crop damage, area farmers pooled resources to have this area of the river dredged. This approach resulted in a straight channel 20 miles long, 10 feet deep, and 10-20 feet wide. The work was completed in the 1930s. While this provided flood protection, the increased flow velocity led to massive erosion, with the channel now ranging to 80 feet deep and 300 feet wide. The high rate of erosion keeps exposing and moving fossil materials.

Lake Ralph Hall, a water supply project of the Upper Trinity Regional Water District, is currently under construction. Mick reported that this impoundment will take away half of the North Sulphur River and inundate some 70% of the watershed. What this will mean for future fossil hunting is uncertain. With less flow and fewer floods, it is possible for more silt and vegetation to accumulate – or less. In the remaining channel, fossils could be exposed less or become easier to find. Time will soon tell, as the reservoir should be completed and filled in the next 2-3 years.

Among the valuable fossil hunting tips provided in the Q&A session, Mick noted the potential flooding hazard: essentially a slot canyon, water levels can rise quickly and egress points are limited, so it pays to be cautious and know the weather conditions. He pointed out that the fossil park has no shade or facilities, so prepare for unbroken sun exposure. On what to bring, Mick suggested something small to dig with, like a long screwdriver, and a shovel (partly for support walking and partly to turn sediment deposits). He often brings a geological hammer. Having seen sandals and crocs taken by the mud, he advises sturdy, fitted footwear.

Going deeper: The Ladonia Fossil Park Facebook page offers recent conditions and many details on hunting and finds
Dallas Paleontological Society Fossil Questions Hotline 817.355.4693
Meet second Wednesday of every month in same room as NTMN
Where to Find and View North Texas Fossils – locations around our area
Upper Trinity Regional Water District information on Lake Ralph Hall

When the recording of the meeting is posted, you will be able to view it here.

Thanks to our guests and members for participating in this month’s meeting. I hope all feel welcome at NTMN.

Take care,
Scott Hudson
North Texas Master Naturalist


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