New Amber Deposit Provides Evidence of Early Paleogene Extinctions, Paleoclimates, and Past Distributions

Abstract

A large, previously unstudied amber deposit in British Columbia dating from the Early to Middle Eocene (50−55 Ma) provides a noteworthy new source of terrestrial invertebrates and other life forms. This deposit contains what are likely the earliest unequivocal ants (members of the family Formicidae), including extinct representatives of Technomyrmex Mayr 1872, Leptothorax Mayr 1855, and Dolichoderus Lund 1831. Discovering Technomyrmex and a corydiinid cockroach, both of which are currently restricted to tropical regions, confirms earlier evidence of warm paleoclimates and past biogeographic distributions in the early Paleogene. Chemical analysis of the amber indicates that the source tree was an araucarian belonging to or near the genus Agathis Salisbury 1807, and demonstrates that this genus survived into the Tertiary in the Northern Hemisphere, since previous records revealed Agathis as a component only of the Cretaceous forests in North America. Comparing the Hat Creek fossil assemblages in this deposit with those from the well-studied western Canadian Late Cretaceous amber deposits offers a unique opportunity to study extinction and speciation events on both sides of the Cretaceous–Tertiary boundary.

Afro-Asian cockroach from Chiapas amber and the lost Tertiary American entomofauna

“…It was very rapidly supported by the discovery of a honey bee in the Miocene sediments of Nevada (Engel et al 2009), a genus extinct in the Americas. Poinar et al (1999) also noticed the Early Tertiary North American extinctions of species of living tropical ant genera Technomyrmex Mayr, 1872, Leptothorax Mayr, 1855 and Dolichoderus Lund, 1831, recorded in the Eocene of British Columbia. These records comprise only the species level, which is insignificant on the present time scale, but Technomyrmex is now, with the exception of a single Central American species (and its abundance in the Dominican amber), limited to the tropics of the old world; Leptothorax is holarctic today; Dolichoderus is cosmopolitan.…”

The Cretaceous Fossil Burmaculex antiquus Confirmed as the Earliest Known Lineage of Mosquitoes (Diptera: Culicidae)

“…If not, the argument against it as a culicid becomes typological. Similar narrow rationale was likewise used to argue that ants preserved in Cretaceous amber were not true Formicidae since they did not possess all of the features of modern ants (Poinar et al 1999). Such an interpretation was critiqued on the basis that it does not recognize stem-groups and transitional forms (Grimaldi & Agosti 2000), which pervade the geological record of life: early ants had short antennal scapes, early birds had teeth, early horses had toes, early snakes had limbs, and early hominids had small brains.…”

New genus of minute Berothidae (Neuroptera) from Early Eocene amber of British Columbia

“…Hat Creek amber ranges from clear to pale yellow (Poinar et al 1999), although it may be bright red (and extremely fragile) in areas next to burn zones. The coal within which it occurs is commonly harder than the amber, making amber extraction difficult without breakage or extensive fracturing.…”

“…The coal within which it occurs is commonly harder than the amber, making amber extraction difficult without breakage or extensive fracturing. Nuclear magnetic resonance (NMR) spectroscopy indicated that the amber was formed by resin from the genus Agathis (Araucariaceae) (Poinar et al 1999); however, NMR spectroscopy indicating the origins of various Cretaceous ambers from Araucariaceae may be problematic (Grimaldi et al 2000). The determination of an araucariaceous origin of Hat Creek amber was further Hat Creek amber is significant primarily for two reasons.…”