Pair of primitive reptile fossils (Barasaurus besairiei)

Pair of primitive reptile fossils (Barasaurus besairiei).
Late Paleozoic (Upper Permian) - Early Mesozoic (Lower Triassic). Approx. 255-250 million years old
Positive and negative assemblage
Fossilized calcareous matrix
Mounted on metal supports
Measurements: 24 × 9,5 cm and 26 × 10 cm

This fossil pair corresponds to a specimen of Barasaurus besairiei, a primitive reptile belonging to the early diapsid group, which inhabited the Earth at a key transitional time between the Upper Permian and Lower Triassic, shortly before and after the largest known mass extinction event.

The assemblage presents both the positive and the negative of the fossil, resulting from the natural splitting of the sedimentary rock that contained it. This phenomenon makes it possible to simultaneously observe the original relief of the skeleton and its complementary impression, offering a particularly complete view of the animal's morphology.

Fossilization occurred through rapid burial processes in fine sediments, where organic matter was progressively replaced by minerals, preserving the bone structure with remarkable precision. The vertebral column, ribs, pelvic girdle and extremities are clearly visible, providing relevant information on the anatomy and locomotion of these early reptiles.

The quality of conservation, together with the paired presentation, reinforces the interest of the set, where scientific value and visual appeal are combined in a representative piece of the great evolutionary processes in the history of the Earth.