Ammonite (and a bunch of other stuff) found in Burmese amber

This find, which was reported in May in the Proceedings of the National Academy of Sciences (click screenshot below for free paper with Unpaywall app; pdf is here, and reference is at bottom) is important not because it gives us a bit of stunning biological knowledge, but because it poses a conundrum: how did an ammonite (a shelled cephalopod and member of a now extinct group) get trapped in amber, which is fossilized tree resin? Ammonites were all marine organisms, while resin comes from trees, which of course grow on land. (The amber also has some marine snails.)

Further, the lump of resin, which is about 100 million years old, contains a number of terrestrial creatures as well: a spider, mites, beetles, a millipede, and so on. How could such a mixture have formed? I’ll show the creatures first and then give the authors’ speculations at the end, so this post be short. First, the paper:

The amber came from a famous amber-mining site in Myanmar, and isn’t that big: the piece examined is 33 mm long, 9.55 mm wide, and 29 mm high, weighing only about 6 grams—that’s 1.3, 0.4, and 1.1 inches respectively, weighing 0.2 ounces. But that small piece contained a wealth of life.  Here’s what the whole thing looked like, and you can see the ammonite at lower right (scale bar is 5 mm):

Using a variety of microscopic techniques, they found these things in it (most pictured below):

  • One ammonite, which was abraded a bit and filled with sand (you can see it in the first picture). This indicates that the ammonite was dead when it was trapped by the resin and later fossilized. The authors identified the ammonite as a juvenile of the genus Puzosia, and, since its occurrence has been dated from other sediments, also dates the amber at about 100 million years old. This is a rare case of amber being dated from the creatures within it.

Here’s figure showing the ammonite (note the sand and broken shell); I’ve added the caption from the paper:

Figure 2 from paper: Ammonite Puzosia (Bhimaites) Matsumoto. (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. (Scale bars, 2 mm.)

  • Four isopods. Isopods are crustaceans that can be marine, freshwater, or terrestrial organisms (on land they’re called “pillbugs”). Two of these appear to be terrestrial and one marine or intertidal. Here they are, with caption:

(Figure 3 from paper): Isopods of uncertain taxonomic affinity, but generally consistent with littoral or supralittoral taxa. (A) Isopod 1. (B) Isopod 2. (C) Isopod 3. (D) Circular structure attached to the dorsal surface of isopod 2. (Scale bars, 1 mm in A and C. Scale bar, 0.5 mm in B and D.)

  • Four marine gastropods (snails), shown below:

(From Figure 4): Gastropods. (A) Mathilda sp. (B) Mathilda sp. (C) Undetermined specimen. (D) Undetermined specimen. (Scale bars, 1 mm.)

  • 22 mites
  • One spider
  • Eight true flies (Diptera)
  • Two beetles
  • One cockroach
  • A millipede
  • And a partridge in a pear tree (only kidding. . .)

These are all of course terrestrial organisms.

Here are some of those fauna with a caption (from Figure 5 of the paper):

Amber inclusions. (B) Acari: Phthiracaridae. (C) Acari: Euphthiracoidea. (D) Araneae: Oonopidae. (E) Diplopoda. (F) Diptera: Phoridae. (G) Hymenoptera: Chrysidoidea. (H) Coleoptera. (I) Blattodea. (Scale bars, 1 mm in E and H. Scale bars, 0.5 mm in B–D, F, and G. Scale bar, 2 mm in I.)

Okay, so here’s the big question: How did both sea creatures and terrestrial creatures get fossilized together in one bit of amber?

The authors give three possibilities (this is my paraphrase of what they say):

1.) There were resin-producing trees (most amber-source trees are confers) growing near a beach. Resin dripped from a tree, trapping the terrestrial stuff as it flowed down the trunk, and then landed on the sand, which had marine gastropod shells and the ammonite shell. The resin was subsequently fossilized. This is supported by the fact that the ammonite is filled with coarse shell sand and had already been abraded, as it would be if it were washed up on a beach (many ammonites inhabited shallow near-shore waters). The amber also contains sand, as if it had dripped on a beach.

2.) A tsunami flooded trees growing near the ocean, bringing with it marine shells that went into globs of resin that already had trapped terrestrial invertebrates. This seems unlikely because, as the authors note, “resin barely solidifies when submerged in water”. Resin that turns into amber has already hardened, and this wouldn’t be the case if this second hypothesis were true.

3.) A tropical storm blew both seashells and sand inland into a forest, and then scenario #1 would apply.  The authors consider this unlikely because, were this true, we would presumably have found more bits of amber containing marine organisms. Yet we have almost none.

Of course we don’t know which possibility is true, but what is clear is that the ammonite was dead when it went into the resin.

Whatever happened, this is a unique piece of amber, and would be worth thousands of dollars on the open market. Fortunately for science, though, it’s been deposited in the Linpoge Amber Museum in Shanghai, China.


Yu, T., R. Kelly, L. Mu, A. Ross, J. Kennedy, P. Broly, F. Xia, H. Zhang, B. Wang, and D. Dilcher. 2019. An ammonite trapped in Burmese amber. Proceedings of the National Academy of Sciences 116:11345-11350.


  1. Posted June 5, 2019 at 10:53 am | Permalink

    Very interesting. If there was an area of sandy dunes invaded by trees that would account for the first solution. I saw such an area on Anglesey the other week where pine woods come right onto a beach – Newborough Beach, Llanfairpwllgwyngyll…

  2. ThyroidPlanet
    Posted June 5, 2019 at 10:58 am | Permalink


  3. Denise Payne
    Posted June 5, 2019 at 11:06 am | Permalink

    That is truly one the most beautiful fossils I have ever seen.

  4. Posted June 5, 2019 at 11:07 am | Permalink

    Is the “Partridge in a Pear Tree” like the M&M’s clause?

  5. Mark Sturtevant
    Posted June 5, 2019 at 11:10 am | Permalink

    I have seen plenty of marine and freshwater sandy areas where the sand is chock full of dead but recent shelly materials. I can see how the various scenarios described could result in a mixing of beach sand with resin from a coastal tree.
    Still way cool, however.

  6. eric
    Posted June 5, 2019 at 11:16 am | Permalink

    Is that too early in time to hypothesize that a land-dwelling, shellfish-eating predator could’ve caught it and then dropped the dead remains near a tree?

    • davidintoronto
      Posted June 5, 2019 at 11:56 am | Permalink

      This was my first thought, too. Somewhat analogous to finding a fish carcass up a tree. But if there’s an eagle’s nest in the tree, there’s no mystery.

  7. Catherine
    Posted June 5, 2019 at 11:25 am | Permalink

    What a treasure—both physically and scientifically beautiful.
    Just letting you know that I always love the science posts–so you’ll keep them coming. Thank you.

    • Steve Pollard
      Posted June 5, 2019 at 12:49 pm | Permalink

      Hear hear! I am guilty of not expressing my appreciation of the science posts as often as I should. But I do read them all, and marvel at many of them – this one more than most.

      So many thanks, Jerry; please keep them coming.

  8. Glenda Palmer
    Posted June 5, 2019 at 11:55 am | Permalink

    I’m enjoying every aspect of this wonderful mystery. It is a shame that scientists are not getting a greater share of the amber that is being removed from that area.

  9. Glenda Palmer
    Posted June 5, 2019 at 11:55 am | Permalink

    I’m enjoying every aspect of this wonderful mystery. It is a shame that scientists are not getting a greater share of the amber that is being removed from that area.

  10. rickflick
    Posted June 5, 2019 at 12:24 pm | Permalink

    Great images. I have (had?) a piece of amber with ancient bugs. Peering into the golden thing can be hypnotic. You think of how these tiny creatures succumbed as the gooey stuff folded around it. For us to enjoy millions of years later.

  11. BJ
    Posted June 5, 2019 at 12:28 pm | Permalink

    This is so. cool.

    Did anyone else immediately get the Jurassic Park theme playing in their head as soon as they saw this? It was an instinctual reaction for me.

    • gravelinspector-Aidan
      Posted June 6, 2019 at 11:54 am | Permalink

      I’d have to watch the film in order to know what the theme is. And then I’d struggle to remember it.

  12. Posted June 5, 2019 at 12:28 pm | Permalink

    I suggested the predator dropping hypothesis yesterday. However adding other marine organisms presents a problem, unless they fell out of a nest or were dropped near one.

    Another option would be a waterspout/tornado. That could pick up marine organisms from either shallow water or off the beach, and then carry them inland and drop them.

    • gravelinspector-Aidan
      Posted June 6, 2019 at 11:59 am | Permalink

      Typical amber deposits show evidence of floating, transport and erosion of the amber grains before deposition into the long-term storage sediment. The mining processes don’t exactly preserve the association between the trees and their dribblings either.
      Some ambers do preserve twig and bark fragments, giving a window into the ecology of the forest sources, but it’s not the clearest of windows.

  13. merilee
    Posted June 5, 2019 at 12:37 pm | Permalink


  14. Gregory Kusnick
    Posted June 5, 2019 at 12:45 pm | Permalink

    Could sampling the ammonite’s shell material provide clues about its provenance and how it got in there?

  15. Posted June 5, 2019 at 12:48 pm | Permalink

    I get a strong wistful feeling when I think of these possible sequences of events playing out 100 million years ago with no one around to see it. As Gerard Manley Hopkins wrote:

    “These things, these things were here and but the beholder wanting.”

  16. Posted June 5, 2019 at 1:01 pm | Permalink

    I believe this list is significant:

    mites, spiders, flies, beetles, cockroaches, and millipedes

    because it predicts, not exclusively, who will still be on this planet after we are gone.

  17. Charles Sawicki
    Posted June 5, 2019 at 1:35 pm | Permalink

    An amazing find! Amber does such a great job preserving the details of tiny trapped creatures.

  18. Mark R.
    Posted June 5, 2019 at 2:02 pm | Permalink

    Wow, what an incredible bit of amber.

    It would make the perfect conversation starter if worn as an amulet necklace.

  19. loren russell
    Posted June 5, 2019 at 4:12 pm | Permalink

    A shame the resin didn’t entrap a live ammonite. I don’t recall reading of soft-tissue fossils of ammonoids, though there are excellent Lagerstatte-style specimens of Cretaceous squids [and, I think, belemnoids and octopus.

    • gravelinspector-Aidan
      Posted June 6, 2019 at 12:16 pm | Permalink

      There are high-quality soft-tissue ammonites preserved. And most of the other classes of the Mollusca. There was a nice couple of belemnoids rattling through my inbox recently … (shuffles through hard drive) (can’t find it) ah, there it is.

  20. DTaylor
    Posted June 5, 2019 at 4:47 pm | Permalink

    So interesting! Thanks for all the identifying information.

  21. Peter (Oz) Jones
    Posted June 5, 2019 at 6:51 pm | Permalink

    Thanks Prof for yet another fascinating & educational science post. The ability to do this forensic examination on so small a piece of amber is mind boggling.

    To channel our export to the USA, Ken Ham, this beautifully combines both “observational” and “historical” science!

    • rickflick
      Posted June 5, 2019 at 7:22 pm | Permalink

      “our export to the USA, Ken Ham,…”

      As the DT tariff has not been payed, Ham will be returned forthwith.

      • Dragon
        Posted June 6, 2019 at 8:22 am | Permalink

        Therein lies the problem with changing the immigration system to a merit-based system. IMHO Ken Ham has no merit. He provides only detrimental effects to our country.
        But in Trump’s opinion, Ken Ham is a fellow con man who sells a fake product for massive riches, and should be at the top of the list.

        Excellent original post. I had guessed at most of the first option. Fascinating.

  22. jahigginbotham
    Posted June 5, 2019 at 9:01 pm | Permalink

    Global Flood?

    • gravelinspector-Aidan
      Posted June 6, 2019 at 12:19 pm | Permalink

      Next question?

  23. Posted June 5, 2019 at 9:28 pm | Permalink


    • Posted June 5, 2019 at 9:30 pm | Permalink

      Thanks for another wonderful post, Jerry.

    • Posted June 5, 2019 at 10:05 pm | Permalink

      Oh, the scientists didn’t like that scenario. How about resin falling from trees, *post* tsunami?

      • gravelinspector-Aidan
        Posted June 6, 2019 at 12:28 pm | Permalink

        That would be a “once in a not very often” event, whereas trees of the appropriate genera drip resin at frequent intervals after predator (herbivore, but still a predator from the tree’s PoV) attack, wind damage, various other causes. So you are far more likely to get samples from the common event than from the rare event.
        Shelly-rich “sand” is almost a stereotype for tropical beaches. Since coral reefs can’t stand significant input of clastic sediment (mud, quartz sand), then the advertising brochure photos almost always have the couple walking along beaches made of crushed shells.

  24. Reggie Cormack
    Posted June 6, 2019 at 7:46 am | Permalink

    As ever playing catch up with WEIT. I do hate to miss a post, Prof, but work and all that does get in the way. Possibly again I’m too late to show appreciation of your science posts, but will do anyway. A lot of these items just wouldn’t come to my attention without your most excellent posts. As to the amber above I reckon a beachside position could do the trick to pick up all manner of life (and ex-life).

  25. eliz20108
    Posted June 6, 2019 at 10:04 am | Permalink

    Fascinating story. Please continue your science stories.

    I was a sociology major. Science stories are unknown territory.

  26. Posted June 6, 2019 at 12:01 pm | Permalink

    As the game said, “POOR WEE CREATURES!” but fascinating about their eventual fate.

  27. Posted June 6, 2019 at 6:16 pm | Permalink

    A late comment to thank you for your science posts. I had read a article about this before, but it didn’t have the scientific details you provided (and, I lazily didn’t go look at the original science paper). Amber is amazing, but I love Ammonites. In fact, my daughter bought a large one for me in Drumheller, Alberta when we were last there visiting the Dinosaur Museum again. The Ammonite is cut in half and has the most amazing colors, some of which shine if in the right light.

%d bloggers like this: