Coastal organisms trapped in amber 99 million years ago

Most amber inclusions are organisms that lived in the forest. It is very rare to find marine life trapped in amber. However, an international research group led by Professor WANG Bo of the Nanjing Institute of Geology and Paleontology of the Academy of Sciences of China (NIGPAS) reported the first known ammonite trapped in the 39; amber PNAS published on May 13th.

Ammonite, a kind of marine animal, was trapped in a 99 million year old amber from northern Myanmar. The amber is 33 mm long, 9.5 mm wide, 29 mm high and weighs 6.08 g. In addition to ammonite, amber also contains a diverse set of organisms living today on land or in the sea, comprising at least 40 animals.

Of the terrestrial fauna found in amber, mites are the most abundant. Also present are spiders, centipedes, cockroaches, beetles, flies and wasps, most of which would have lived on the forest floor.

Among the marine fauna, besides the ammonite itself, are sea snails and sea slaters. The slaters are like those who live by the sea today.

The researchers used X-ray micro-computed tomography (micro-CT) to obtain high-resolution, three-dimensional images of ammonite, including its dimpled sutures, important for the identification of ammonites.

They discovered that ammonite is a juvenile puzosia (Bhimaites) and that its presence in amber favors a recent Albian-Early Cenomanian age for the amber deposit. This discovery represents a rare example of dating using amber inclusions.

But how is it that ammonite, a dead squid parent living in the sea, has found itself in a piece of amber that also contains terrestrial animals? The ammonite shells and sea snails offer possible clues.

The shells are all empty, without soft tissue. The organisms had long since died when they were engulfed by the resin. The outer envelope of the ammonite is broken and the entrance to the envelope is full of sand. Amber also contains extra sand.

The most likely explanation for the occurrence of marine and terrestrial organisms in amber is that a sandy beach covered with shells was located near the resin producing trees. The flying insects were trapped in the resin while she was still on the tree. As the resin flowed down the trunk, she captured organisms living at the foot of the tree. Reaching the beach, he buried shells and trapped the slats that lived there

###