Coastal organisms trapped in 99-million-year-old amber

Coastal organisms trapped in 99-million-year-old amber
Amber piece showing most large inclusions Credit: NIGPAS

Most amber inclusions are organisms that lived in the forest. It is very rare to find sea life trapped in amber. However, an international research group led by Prof. Wang Bo from the Nanjing Institute of Geology and Palaeontology of the Chinese Academy of Sciences (NIGPAS) reported the first known ammonite trapped in amber in a study in PNAS published on May 13.

The ammonite, a kind of sea animal, was trapped in 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. Besides the ammonite, the amber also encases a diverse assemblage of organisms that today live on land or in the sea, including at least 40 individual animals.

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

Of the marine fauna, in addition to the ammonite itself, sea snails and sea slaters are present. The slaters are like those living on the seashore today.

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

They found that the ammonite is a juvenile Puzosia (Bhimaites) and its presence in the amber supports a late Albian-early Cenomanian age for the amber deposit. This discovery represents a rare example of dating using amber inclusions.

Coastal organisms trapped in 99-million-year-old amber
(A) Lateral view under light microscopy. (B) Flattened sutures reconstructed by microtomography. (C) Microtomographic reconstruction, apparent view. (D) Microtomographic reconstruction, surface rendering; (E) Microtomographic reconstruction, virtual section Credit: NIGPAS

But how on earth did the ammonite, an extinct sea-dwelling relative of squid, get preserved in a piece of amber that also contains land-based animals? The ammonite and sea snail shells offer possible clues.

The shells are all empty with no soft-tissue, so the organisms were long dead by the time they were engulfed by resin. The outer shell of the ammonite is broken away and the entrance of the is full of sand. The amber also contains additional sand.

The most likely explanation for the appearance of both marine and terrestrial organisms within the amber is that a sandy beach covered with shells was located close to resin-producing . The were trapped in the resin while it was still on the tree. As the resin flowed down the tree trunk, it trapped that lived near the foot of the tree. Reaching the beach, it entombed shells and trapped the slaters living there.


Explore further

First examples of Iberian prehistoric 'imitation amber' beads at gravesites

More information: Tingting Yu el al. An ammonite trapped in Burmese amber. PNAS (2019). www.pnas.org/cgi/doi/10.1073/pnas.1821292116
Citation: Coastal organisms trapped in 99-million-year-old amber (2019, May 13) retrieved 21 May 2019 from https://phys.org/news/2019-05-coastal-million-year-old-amber.html
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
909 shares

Feedback to editors

User comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more