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Amber of Myanmar in Southeast Asia proves to be an incredibly rich resource for examining the natural world from 100 million years ago. During the past year, there have been frogs, snails, a snake, strange feathers and pretty crazy insects. What do all have in common? They inhabit the earth.
But now, paleontologists have discovered something truly strange in a small piece of Myanmar cretaceous amber: sea creatures alongside terrestrial creatures.
This represents four sea snails and a juvenile marine ammonite from the ocean. Four intertidal isopods (and three other possible isopods), located in the area between high tide and low tide, were also trapped, as well as the sand from the beach.
(Bo Wang)
From the ground, amber contains 22 mites, which appears to be a goblin spider, 12 adult insects (eight flies, two beetles, a parasitic wasp and a cockroach) and a centipede. And everything is in a block of 33 millimeters by 9.5 millimeters by 29 millimeters.
This is a remarkable assemblage of creatures.
"It is rare to find aquatic organisms in amber and extremely rare, not to mention the macroscopic marine organisms mixed with intertidal, terrestrial and potentially freshwater aquatic organisms," the researchers wrote.
The play is certainly mysterious. Palaeontologists, for example, were unable to determine their age.
The dating of uranium-lead zircons in the volcanic rock matrix in which amber lies is about 98.8 million years, but a layer of sandstone above the amber would contain a fossilized ammonite that would have arrived on the scene. 113 million years, and not have lived more than 100.5 million years.
(Yu et al., PNAS, 2019)
The ammonite in question was neither described nor illustrated in the document that mentions it and no one was able to find the fossil itself to conduct a further examination.
It is possible that the amber itself is older than the bed from where it comes from, so it could be over 113 million years old. This is a question that remains unresolved at the moment.
Fortunately, it is a little easier to exactly reconstruct the number of different creatures that have found themselves in the same piece of amber.
Here is the index: the shells of ammonite and marine gastropods are slightly abraded, a large part of the ammonite shell has been lost and the opening clogged with sand; there are also no signs of soft tissue belonging to ammonite or gastropods.
And the resin will not solidify properly when it is submerged in water. It is therefore unlikely that a drop will fall into the water and catch the marine animals before turning into amber.
Intertidal Isopods. (Yu et al., PNAS, 2019)
The paleontologists therefore deduced that the marine creatures we see here were already dead, their shells were destroyed by the tides and were washed away on a beach. It is there that they found themselves caught in a tree resin ball.
"The exceptional presence of macroscopic marine macrofossils in the resin suggests that the amber forest was growing near a coast, possibly close to a beach, and could have been the object of a large number of species. exceptional events, "the researchers wrote.
"The shells can record an unusually high tide, possibly caused by a storm, or even a tsunami or other high-energy event." Otherwise, and more likely, the resin fell on the beach of coastal trees unusually, surviving the high energy beach environment to be preserved as amber. "
And it is like that that they stayed for millions of years, buried under a sandstone bed in Myanmar. It is possible that we may not be able to learn more about how such amber inclusions occur as long as other animals containing marine animals have not been discovered.
But what a series of events absolutely spectacular.
The search was published in PNAS.
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