In situ Baltic amber is found within the Prussian Formation, with the main amber bearing horizon being referred to as "Blue Earth", so named due to its glauconite content. The formation is exposed in the northern part of the Sambia Peninsula in Kaliningrad.
Different authors have given estimates of 40-47 million years ago and 35-43 million years ago as the age of the Prussian Formation.[1]
Paleobiology
Numerous extinct genera and species of plants and animals have been discovered and scientifically described from inclusions in the Prussian Formation.[3] Inclusions of insects make up over 98% of the animals preserved in the amber, while all other arthropods, annelids, molluscs, nematodes, protozoans contribute less than 0.5% of the animals. Vertebrates are another 0.5% of the animals included and mostly are represented by mammal fur, feathers, and reptiles.[4]
^Weitschat, W.; Wichard, W. (2002). Atlas of Plants and Animals in Baltic Amber. Pfeil. ISBN978-3931516949.
^Weitschat, W.; Wichard, W. (2010). "Chapter 6: Baltic amber". In Penney, D. (ed.). Biodiversity of Fossils in Amber from the Major World Deposits. Siri Scientific Press. pp. 80–115. ISBN978-0-9558636-4-6.
^Heinrichs, J; Schmidt, AR; Schäfer-Verwimp, A; Gröhn, C; Renner, MAM (2015). "The leafy liverwort Notoscyphus balticus sp. nov. (Jungermanniales) in Eocene Baltic amber". Review of Palaeobotany and Palynology. 217: 39–44. Bibcode:2015RPaPa.217...39H. doi:10.1016/j.revpalbo.2015.02.006.
^Heinrichs, J; Hedenäs, L; Schäfer-Verwimp, A; Feldberg, K; Schmidt, AR (2014). "An in situ preserved moss community in Eocene Baltic amber". Review of Palaeobotany and Palynology. 210: 113–118. Bibcode:2014RPaPa.210..113H. doi:10.1016/j.revpalbo.2014.08.005.
^ abcdeWheeler, W. M. (1914). "The Ants of the Baltic Amber". Schriften der Physikalisch-Ökonomischen Gesellschaft zu Königsberg. 55 (4): 56–59.
^ abEskov, K. Y.; Zonstein, S. L. (2000). "The First Ctenizoid Mygalomorph Spiders from Eocene Baltic Amber (Araneida: Mygalomorphae: Ctenizidae)". Paleontological Journal. 34 (3): S268–S274. Part 1; part 2, PDF.
^Makarkin, VN; Wedmann, S; Weiterschan, T (2014). "First record of the family Ithonidae (Neuroptera) from Baltic amber". Zootaxa. 3796 (2): 385–393. doi:10.11646/zootaxa.3796.2.10. PMID24870683.
^Alekseev, VI; Lord, NP (2014). "A new species of Xylolaemus (Coleoptera: Zopheridae: Colydiinae) from Baltic amber". Baltic Journal of Coleopterology. 14 (1): 97–102. ISSN1407-8619.