Giant fossil seeds are shedding light on the ancient migration of plants

Giant fossil seeds discovered in Indonesian Borneo have shed light on ancient plant migration and the evolution of Southeast Asian and Australian rainforests, according to researchers from Penn State University. The fossils, dating back 34 to 40 million years, belong to an extinct legume genus closely related to the modern Castanospermum, the black bean tree found in northern Australia and neighboring islands. The findings, published in the International Journal of Plant Sciences, suggest that the ancestors of the black bean tree migrated from Asia to Australia during the tectonic collision that brought these landmasses together.

The collision between the Southeast Asian and Australian tectonic plates occurred approximately 20 million years ago and resulted in a significant exchange of plant and animal species between the continents. This research provides the first evidence of a plant lineage moving from Asia to Australia following this collision. These fossils are also the oldest confirmed legumes belonging to the bean family from the Malay Archipelago and the first fossil record of plants related to the black bean tree.

The scientists explain that the limited direct evidence of plant movement from Asia to Australia is due in part to a poor plant fossil record in the Malay Archipelago, which encompasses countries like Indonesia and the Philippines. However, the researchers were fortunate to partner with paleontologists from the Institut Teknologi Bandung in Java, Indonesia, who facilitated the collection of these precious fossils.

The fossil seeds, which are among the largest in the fossil record, were given the name Jantungspermum gunnellii. Analyzing these ancient seeds using CT scans and taxonomic identification, the researchers determined that they resemble modern Castanospermum seeds, with unique characteristics matching no other known legume group.

These findings contribute significantly to our understanding of legumes' presence in Southeast Asia and fill an important gap in the region's fossil record. Ongoing research and increased fossil sampling are necessary to further explore the neglected paleobotanical potential of the Malay Archipelago and gain insights into the evolution of tropical ecosystems, as deforestation threatens these diverse biomes.

Earlier SSP reported that the world's oldest calendar found carved in Turkey.