Stephanie Jennings
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The Heard Museum Presents:  Texas Nessie

In May of 1991, avid fossil collector Mike Donovan made an amazing find in Collin County: the partial skeleton of a plesiosaur. He nicknamed the fossil “Texas Nessie” and spoke often of how he hoped the bones would eventually be displayed in a museum, where they could be viewed and appreciated.

Nearly twenty years after that remarkable discovery, Donovan’s dream is now a reality. The lengthy, complicated process began in September of 2015 when Darlene Sumerfelt, Heard Paleontological Lab Manager and Lead Preparator, was contacted by Debera Donovan regarding her late husband’s fossil collection, which contained a wide variety of bones in addition to the partial skeleton of a plesiosaur. After the bones were donated to the Heard Museum by the Debera Donovan Foundation on September 30, 2015, Sumerfelt and plesiosaur expert Mike Polcyn of SMU, performed an initial evaluation. That analysis revealed that approximately 40% of the skeleton was present and that the plesiosaur was a species of Trinacromerum. The skull bones were unique in that they were not compressed, as is the case with most other known specimens of this type of plesiosaur. In fact, the preservation and completeness of this specimen provides anatomical details that will help illuminate the relationships among this group of plesiosaurs. Additionally, it may provide clues about how these animals were evolving and dividing up the ecosystem about 93-million-years-ago in what is now the DFW area. This makes the specimen not only a beautiful example of a plesiosaur fossil, but also one with great scientific value as well.

Specific locality information for the specimen is lacking and can only be narrowed to the central western part of Collin County. Fortunately, during prep of the bones, Sumerfelt found several ammonite imprints in the matrix surrounding the bones. The imprints were sent to an ammonite expert who identified them as Collignoniceras woollgari regulare, which provides a precise stratigraphic placement. Therefore, this specimen was likely from the lowest ten meters of the Arcadia Park Formation of the Eagle Ford group, which provides an age approximation of 93 million years old.

Preparation of the plesiosaur bones took place over a four-year period using pneumatic tools called airscribes to slowly chip away the rock encasing the bones. The prep team led by Sumerfelt included Joan and Richard Sheppard and Fletcher Wise. As the prep moved forward, Mike Donovan’s dream of seeing this fossil become a full mount museum exhibit became Sumerfelt’s dream as well. Funds would have to be raised as a full 14-foot plesiosaur museum mount and exhibit enclosure would be well beyond the means of a non-profit museum. Thankfully, funding was obtained from many sources which included the Dallas Paleo Society, and the project moved forward, hiring Triebold Paleontology in Woodland Park, Colorado, to mount the bones for display. Soon after delivery to Triebold, the COVID shutdown began, and the project went on hold. Work resumed a few months later and was completed in February 2021.

During the time the bones were in Colorado, artist Pamela Riddle was busy creating a beautiful digital wall mural for the exhibit. The mural is 22 feet long and depicts a plesiosaur as well as other creatures from the time this plesiosaur lived.

In late February 2021, Triebold Paleontology delivered and installed the 14-foot-long plesiosaur.  Sumerfelt and her team designed the text panels for the exhibit and contractors were hired to do the exhibit enclosure and lighting. 

Decades after that exciting moment when Mike Donovan first discovered and excavated this epic example of an ancient marine predator, his dream of a museum display has finally become a reality. Thanks to six years of coordinated efforts of dedicated experts and volunteers, this exhibit showcases a beautiful, scientifically important specimen, representing dreams fulfilled, thousands of hours of labor, and gracious, generous community donations. Bringing Texas Nessie to the Heard Museum has truly been a labor of love.

The Heard would like to thank the Debera Donovan Foundation for this generous gift. 

The exhibit is now open, and “Nessie” is ready to pose with you with her fabulous, toothy grin! This exhibit is included in general admission and free for Heard Museum members.

About Plesiosaurs

In life, this vicious predator had a streamlined body and would have looked much like a giant penguin swimming through the water. Plesiosaurs propelled themselves with four flippers. The two in front were for propulsion and the two rear were used like rudders for steering. Each flipper moved in a manner similar to a penguin’s wing, sweeping backward to quickly move through the water. Penguins are among the speediest oceanic predators as they “fly” through the water. Plesiosaurs might have been as fast or faster with their two pairs of “wings.”

This plesiosaur lived in the Cretaceous Period, 93 million years ago, in a large interior seaway that split the continent of North America into two landmasses. The interior seaway stretched from the Gulf of Mexico to the Arctic Ocean in the north. The seaway was filled with abundant marine life including large, predatory, marine reptiles such as the plesiosaur in our exhibit. This is why this huge sea creature was found right in our own backyard!

Soft tissue impressions have been found showing that plesiosaur skin had a smooth surface absent of scales.

Based on the interlocking design of their teeth, it is hypothesized that their diet probably included fish. Their long, curved teeth could have enabled them to impale and hold their slippery prey. Plesiosaurs did not have gills. They were air-breathing reptiles. They could, however, remain submerged for long periods. They were also viviparous, meaning they gave birth to live young. Evidence has been found of an adult female plesiosaur with a fetus inside.

About Heard Natural Science Museum & Wildlife Sanctuary

The Heard was founded in 1967 by Bessie Heard. Miss Heard was 80 years old when she saw the need to preserve a place where future generations could experience nature. Today, the Heard's mission of bringing nature and people together to discover, enjoy, experience, restore, and preserve our priceless environment is carried out through education, particularly of young people, which emphasizes an appreciation of nature and its conservation.  For more information, visit

Marketing & Communications Director at Heard Natural Science Museum & Wildlife Sanctuary in McKinney, Texas. - Contact Stephanie at  
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