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20.2" Full Dorsal Dimetrodon Vertebra - Spine Sail

20.2" Full Dorsal Dimetrodon Vertebra - Spine Sail


With a fearsome jaw and reptilian appearance, Dimetrodon is often mistaken for a dinosaur. However, this family of Early Permian Age species falls into a disparate taxonomic clade known as Synapsids which includes Mammals. The purpose of Dimetrodon's iconic spine sail is unknown, though speculation ranges from thermoregulation to sexual dimorphism, and perhaps even locomotion.

Above: Anterior view of the 20.2" Full Dorsal Vertebra

This is a 20.2" Full Dorsal Dimetrodon Vertebra. It comes from private lands in West Texas, USA. This region, known as the Texas Red Beds, contains one of the most complete fossil records of the Early Permian and dates to roughly, 280,000,000 years old. The diagram below shows the location of this particular vertebra.

As you can see from the pictures, this is a magnificent specimen. Truly one of a kind in both material and presentation.

This specimen ships in a custom foam container and contains printed copies of the documentation you see here on the site. A large certificate of authenticity will also be included, along with a copy of the book Relics which has a feature on Dimetrodon.

More About Dimetrodon

"The apex of the spine in this species is slender, and apparently was flexible. The utility is difficult to imagine." ~ Edward Drinker Cope, 1886

Above: Artist's concept of Dimetrodon (Source: Mini Museum)

The Permian Age represents a radical change to life in response to a more varied climate across the planet. Diversification of plants, the first true bony fish, and on land the evolution of amphibian life to pure terrestrial animals. In the oceans, we see the first true bony fish. On land, the evolution of amphibian life gives way to pure terrestrial animals, including Dimetrodon.

With a fearsome jaw and reptilian appearance, Dimetrodon is often mistaken for a dinosaur. However, this apex predator of the Early Permian Age is part of a major group of animals known as Synapsids. In addition to reptile-like creatures such as Dimetrodon, Synapsids also includes all mammals... and yes, humans too!

Dimetrodon is one of the first terrestrial vertebrates to develop multiple types of teeth, including tightly compressed, recurved teeth with sharp cutting edges. Known as ziphodont teeth, scientists speculate this development was a result of a new, refined feeding style in which flesh is sheared from the bones by pulling instead of direct, bone-crushing force.

Above: (a) Royal Ontario Museum (ROM) 1797 tooth, labial view, mesial carina to the right. (b) ROM 1797, scanning electron microscope (SEM) of posterior carina, apical up. (c) ROM 6039, SEM of posterior carina, basal up. (d) ROM 6039Z, posterior carina, apical left. Viewed under cross-polarized light with a lambda plate and oblique illumination. (e) ROM 6039K, anterior carina, apical left. Viewed under plain polarized light. c, crack; d, dentine; e, enamel; g, globular dentine; is, interdentinal sulcus; k, keel. Scale bars, (a) 0.5 cm, (b–e) 0.5 mm. (Source: Nature, Brink, Kirstin S., and Robert R. Reisz. "Hidden dental diversity in the oldest terrestrial apex predator Dimetrodon.")

Over the course of 20 million years, there were many species of Dimetrodon ranging in size and decked with a variety of iconic spine sail shapes. The purpose of this structure has been debated for many decades. Early theories centered on thermoregulation while more recent studies have shown that the spines lacked the necessary channels for carrying blood vessels.

Above: A small Spinosaurus vertebra and neural spine sail (left) compared to the 20.2" Dimetrodon Vertebra (right). Examples of convergent evolution in radically different species.

In recent decades, the discussion has moved toward the sail's role in sexual dimorphism, but science is always testing new ideas and methods. As an example, a study in 2012 in conjunction with NASA's Jet Propulsion Laboratory suggests the sail may have served as a spring-like energy storage device for fast locomotion.

Further Reading

Cope, Edward Drinker. "Second contribution to the history of the Vertebrata of the Permian formation of Texas." Proceedings of the American Philosophical Society (1880): 38-58.

Rega, Elizabeth A., et al. "Healed fractures in the neural spines of an associated skeleton of Dimetrodon: implications for dorsal sail morphology and function." Fieldiana Life and Earth Sciences (2012): 104-111.

Brink, Kirstin S., and Robert R. Reisz. "Hidden dental diversity in the oldest terrestrial apex predator Dimetrodon." Nature communications 5 (2014).


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