An ammonite trapped in Burmese amber

Abstract

Amber is fossilized tree resin, and inclusions usually comprise terrestrial and, rarely, aquatic organisms. Marine fossils are extremely rare in Cretaceous and Cenozoic ambers. Here, we report a record of an ammonite with marine gastropods, intertidal isopods, and diverse terrestrial arthropods as syninclusions in mid-Cretaceous Burmese amber. We used X-ray–microcomputed tomography (CT) to obtain high-resolution 3D images of the ammonite, including its sutures, which are diagnostically important for ammonites. The ammonite is a juvenile Puzosia (Bhimaites) and provides supporting evidence for a Late Albian–Early Cenomanian age of the amber. There is a diverse assemblage (at least 40 individuals) of arthropods in this amber sample from both terrestrial and marine habitats, including Isopoda, Acari (mites), Araneae (spiders), Diplopoda (millipedes), and representatives of the insect orders Blattodea (cockroaches), Coleoptera (beetles), Diptera (true flies), and Hymenoptera (wasps). The incomplete preservation and lack of soft body of the ammonite and marine gastropods suggest that they were dead and underwent abrasion on the seashore before entombment. It is most likely that the resin fell to the beach from coastal trees, picking up terrestrial arthropods and beach shells and, exceptionally, surviving the high-energy beach environment to be preserved as amber. Our findings not only represent a record of an ammonite in amber but also provide insights into the taphonomy of amber and the paleoecology of Cretaceous amber forests.

Generalist Pollen-Feeding Beetles during the Mid-Cretaceous

“…findings of marine and freshwater fossils in Myanmar amber, which suggests that the local resinous forest was present adjacent to a coastal embayment or a deltaic environment (Schmidt et al, 2018;Xing et al, 2018;Yu et al, 2019). The hydrophyte niche occupied by Nymphaeaceae extended deep into the Early Cretaceous (Friis et al, 2011) and probably included attractants such as petaloid floral structures with embedded nectar, emission of fruity odors, and receptacular thermogenesis that sequester pollinating insects (Seymour and Matthews, 2006).…”

An unusual 100-million-year old holometabolan larva with a piercing mouth cone

“…atrickmuelleri'. Type stratum and corresponding age: unknown stratum, 98.8 million years, lowermost Cenomanian, lowermost Upper Cretaceous, after Shi et al (2012), stratigraphically supported by a recent record of an ammonite shell of Puzosia (Bhimaites) in Burmese amber (Yu et al, 2019).…”

“…In fact, aquatic larvae of Megaloptera (Sialidae) and Neuroptera (Nevrorthidae; Sisyridae) have been found preserved in amber (Wichard, Gröhn & Seredszus, 2009). In recent years, numerous animals which would be considered unlikely to be preserved in fossiliferous resins, such as non-avian forms of Dinosauria and birds (Xing et al, 2016) and an ammonite shell (Yu et al, 2019) have been found. In summary, we cannot really narrow down how the fossil larva might have lived, though aquatic habitats do present an attractive possibility.…”

New record of podocopid ostracods from Cretaceous amber

“…An ammonite shell preserved in Burmese amber argues that the Burmese amber forest was located near a dynamic and shifting coastal environment ( Yu et al, 2019 ), a conclusion supported by the occurrence of a marine myodocopan ostracod ( Xing et al, 2018 ). Also, semi-aquatic and aquatic insects occur in Burmese amber, including Ochteridae (Hemiptera), Heteroceridae (Coleoptera), Chresmododea and Gerridae (Hemiptera), Dytiscidae and Gyrinidae (Coleoptera), adults and larvae of Odonata, larvae of Psephenidae, Trichoptera, and Ephemeroptera ( Zhang, 2017 ; Xing et al, 2018 ; Schädel, Müller & Haug, 2020 ).…”