1" Detailed Cardiospermum Coloradensis Balloon Vine Fossil Plant Leaf Eocene Age UT

Cardiospermum coloradensis Leaf

Cardiospermum coloradensis is an extinct member of the soapberry family preserved within the renowned Green River Formation, dating to the early Middle Eocene, approximately 53–48 million years ago. This specimen was collected in Colorado, USA, from finely laminated lake shales that are celebrated for their remarkable fossil preservation. The leaf exhibits a rich, dark brown coloration that contrasts beautifully against the pale, sandy-toned shale matrix typical of these deposits.

Belonging to the soapberry family (Sapindaceae), a group recognized today for species bearing bright red or inflated fruits, Cardiospermum represents a lineage with deep evolutionary roots. During the Eocene, members of this family formed part of the lush vegetation surrounding expansive freshwater lakes that once covered parts of Utah, Colorado, and Wyoming.

Although the Green River Formation is most famous for its spectacular fish fossils, it also preserves a diverse assemblage of plants, invertebrates, reptiles, mammals, and even stromatolites. Plant fossils are abundant within these shales, demonstrating that soapberry-related species were a notable component of lake-margin ecosystems. Occasionally, fossil leaves from this formation may include faint insect impressions, though insects remain comparatively rare.