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First Evidence of Color in Sauropods

Juvenile Diplodocus had speckled, patterned skin, as revealed by newly discovered fossil melanosomes.

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New Research Reveals the First Evidence of Color in Sauropods

This news article is based on the Journal Article (Gallagher et al, 2025) from Royal Society Open Science

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For more than a century, sauropods—those massive, long-necked dinosaurs like Diplodocus and Apatosaurus—have been imagined as gray, uniform giants with wrinkly, elephant-like skin and no bold markings. They’ve long been assumed to be relatively plain animals. But new research published in 2025 by Tess Gallagher and colleagues has changed that picture. For the first time, scientists have identified fossilized melanosomes—pigment-producing organelles—in sauropod skin. These microscopic structures indicate that juvenile Diplodocus may have displayed far more complex coloration than previously imagined, including speckling or patchy pigmentation. The study also reveals two distinct melanosome shapes, hinting at unexpected color diversity in sauropods.

The Morrison Formation and the Mother’s Day Quarry of Montana

The fossils behind this discovery come from a remarkable site known as the Mother’s Day Quarry in Montana. This quarry is part of the Morrison Formation, a deposit dating to roughly 156–146 million years ago that represents one of the richest windows into Jurassic life. Spanning much of the western United States, the Morrison preserves vast floodplains, seasonal waterways, fern meadows, and conifer forests. It is home to iconic dinosaurs such as Stegosaurus, Allosaurus, and the great herds of sauropods that dominated the ecosystem.

Within this formation lies the Mother’s Day Quarry, a site composed almost entirely of juvenile Diplodocus fossils. It is one of the only locations in the world to preserve juvenile sauropod skin in exceptional detail. Excavations have uncovered countless bones from young diplodocids—ranging from cow-sized individuals to others approaching the size of modern elephants—all preserved under unique taphonomic conditions.

Evidence suggests these animals died during a prolonged dry spell, likely congregating around a shrinking or completely dried-up watering hole. Their bodies remained exposed long enough for the skin to dry and shrink before burial, while scavenging theropods left bite marks, shed teeth, and even foot impressions in the skin. When the rainy season returned, a mudflow or debris flow washed in, transporting the remains and eventually burying them. The fine-grained mudstone and siltstone later protected delicate tissues, allowing rare patches of epidermis to fossilize.

Diplodocus Scales: What We Knew Before This Study
Lead author Tess Gallagher has conducted extensive research on the preserved dinosaur skin from this quarry. Her earlier work revealed that Diplodocus possessed a wide variety of scale shapes, similar to those of modern crocodiles (Gallagher et al., 2021). Different parts of the body displayed distinct scale patterns, including mosaic-like arrangements along the sides and limbs. Some scales even preserved epidermal papillae—small bumps that may have added texture. This shifted paleontologists’ view away from elephant-like sauropod skin toward something more crocodilian. However, until now, no preserved melanosomes—the pigment-bearing structures that indicate coloration—had ever been found in sauropod skin.

What the New Study Found
Scientists using scanning electron microscopy (SEM) identified oblong and disc-shaped microbodies consistent with melanosomes. These structures are carbon-rich, embedded within layered fossilized skin, and closely match pigment organelles in other fossils. If both forms represent true melanosomes, this marks the first evidence of pigment diversity in dinosaur scales—previously seen only in feathers.

The study also reveals two distinct epidermal layers: a clay-rich upper layer interpreted as the stratum corneum, and a deeper, carbon-rich layer containing melanosomes. This explains why earlier surface tests failed—the pigment structures were hidden below the outer layer.

Melanosomes appear in clusters spaced roughly 100 microns apart, suggesting speckled or patchy coloration rather than a uniform tone. Although the preserved skin patches are too small to map an entire animal, this discovery provides the first real constraints on sauropod color.

In modern animals, diversity in melanosome shape often correlates with higher metabolic rates. If juvenile Diplodocus possessed similar structures, it may hint at elevated metabolism in young sauropods, supporting theories that they were at least partially endothermic.

What Color Were Juvenile Diplodocus?
While exact skin color cannot be reconstructed without preserved pigments, the melanosomes suggest a reddish-brown and/or black tone. Diversity in microbody shapes may indicate more complex shading or patterning. Speckles, patches, or mottled coloration are all plausible and may have helped young sauropods camouflage within their environment—critical for animals vulnerable to predators.

This groundbreaking research opens the door to more accurate full-body reconstructions of sauropods. Juvenile Diplodocus may not have been dull, gray giants after all, but patterned, speckled animals blending into the Jurassic world.

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Journal Articles:
Tess Gallagher, Dan Folkes, Michael Pittman, Tom G. Kaye, Glen W. Storrs, Jason Schein; Fossilized melanosomes reveal colour patterning of a sauropod dinosaur. R Soc Open Sci. 1 December 2025; 12 (12): 251232. doi.org/10.1098/rsos.251232.

Gallagher T, Poole J, Schein JP. 2021. Evidence of integumentary scale diversity in the late Jurassic Sauropod Diplodocus sp. from the Mother’s Day Quarry, Montana. PeerJ 9:e11202 doi.org/10.7717/peerj.11202.

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