15/09/2025
來自1.2億年前、世上首見第一個雙頭恐龍的化石標本。
Meet the Hyphalosaurus, a long-necked swimmer from ancient lakes of Early Cretaceous China over 120 million years ago This sleek reptile glided through deep freshwater using a flattened tail and paddle-like limbs to chase fish and arthropods; its long neck and narrow jaw made it efficient at sideways strikes in murky water
Hyphalosaurus is part of the choristodere group, a line of reptiles adapted to life in water rather than land It had more than fifty vertebrae in its tail, webbed feet, and scales that suggest a smooth, hydrodynamic skin These adaptations meant it was highly aquatic, rarely seen outside deep lake beds It was abundant in the Jehol Biota, known from many specimens ranging from embryos to adults
One of the most fascinating finds is a tiny Hyphalosaurus specimen with two heads and two necks, joined at the body beneath the pectoral girdle This is the oldest known instance of a developmental anomaly called axial bifurcation in a reptile fossil record The creature was either an embryo or very young and did not live long but its preservation gives rare insight into how malformations occurred in deep time
Strange fact Even though Hyphalosaurus fossils are very common, soft-tissue details like webbing between toes, skin textures, and embryonic structures are preserved only in a few; the two-headed specimen stands out not just for the anomaly but because it’s part of that small group where even delicate developmental details survived through volcanically influenced sediments
