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An international team of paleontologists has discovered a piece of amber containing beautifully preserved ammonite, several marine and terrestrial organisms that lived 99 million years ago (Cretaceous period).
Amber piece of 99 million years of northern Burma. Image Credit: Nanjing Institute of Geology and Paleontology.
The ammonite-containing piece of ammonite comes from a mine located near the village of Noije Bum, in the city of Tanaing, in northern Myanmar. It has a length of 33 mm, a width of 9.5 mm and a height of 29 mm. Its mass is about 6 g.
The specimen was analyzed by Professor Bo Wang of the Nanjing Institute of Geology and Paleontology and his colleagues from China, the United States, France and the United Kingdom.
The researchers used X-ray micro-computed tomography to obtain high-resolution 3D images of ammonite, including its sutures, which are of diagnostic importance for ammonites.
They found that ammonite belongs to Puzosia, an ammonite genus that first appeared in the Upper Albanian Cretaceous period (between 113 and 100 million years ago) and varied until the Cenomanian period (between 100 and 94 million years ago) .
"The ammonite is a juvenile, has a maximum preserved diameter of 12 mm and seems to retain the original aragonitic shell, because of its appearance in reflected light," they said.
"Its presence in amber favors a late early Cenomanian Albian age for the amber deposit. This discovery represents a rare example of dating using amber inclusions. "
L & # 39; ammonite Puzosia sp .: (A) side 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. Scale bars – 2 mm. Image credit: Yu et al, doi: 10.1073 / pnas.1821292116.
The team also found at least 40 arthropod individuals in the amber sample from both terrestrial and marine habitats, including crustaceans, mites, spiders and centipedes, and several insects, including cockroaches, beetles, true flies and wasps.
"But how is ammonite, an extinct parent of squid living in the sea, and other marine creatures preserved in a piece of amber that also contains terrestrial animals? The ammonite shells and sea snails offer possible clues, "paleontologists said.
"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 is that a sandy beach covered with shells was located near trees producing resin. The flying insects were trapped in the resin while she was still on the tree. "
"As the resin flowed along the tree trunk, it captured organisms living at the foot of the tree. Arriving at the beach, he buried shells and trapped laths that live there.
The discovery is reported in an article of the Proceedings of the National Academy of Sciences.
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Tingting Yu et al. Ammonite trapped in Burma's amber. PNAS, published online May 13, 2019; doi: 10.1073 / pnas.1821292116
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