AN EXQUISITELY PRESERVED FROG TONGUE WITH LAST INSECT MEAL AND OTHER EXCEPTIONAL FROZEN BEHAVIORS IN DOMINICAN AMBER

Amber, solidified plant resin, has long been known for its remarkable preservation power. A wide variety of animals and plants have been found in amber, ranging from single-cell organisms, such as bacteria and protists, to vertebrates, including reptiles and frogs, as well as bird feathers and mammal hairs. Dominican amber is renowned for its clarity and taxonomic breadth of biological inclusions. Nearly every insect order and a variety of small vertebrates have been found in Dominican amber. Perhaps as exciting as single organisms being preserved are examples of frozen behaviors, evident or implied, in this fossil resin.

Though uncommon, examples of numerous frozen behaviors have been found in Dominican amber, ranging from various types of paleosymbioses, predator-prey interactions, defensive and social behaviors, reproduction, and reflexes. Several exquisite examples of exceptional frozen behaviors are presented, with a special focus on a complete frog tongue with last insect meal, a multi-phase swarm of dolichopodid flies, and an Acropyga queen ant carrying a mealy bug. Other frozen behaviors examined include an Azteca ant carrying an ant larva and ant pupa, pseudoscorpions riding wood-boring beetles (phoresis), juvenile allantonematid nematodes emerging from a fly (parasitism), and a spider carrying an egg sac (parental care).

Only approximately ten frogs have been found in amber. This is the first frog specimen in amber, and perhaps the first vertebrate specimen found with a complete, visible structure we interpret as a tongue. The preservation of the soft tissue is phenomenal, revealing intricate details of its muscular structure, surface, possible attachment flaps, and absence of bony structures. At the upper surface of the tongue, there are several partial arthropods (including a portion of a cricket’s leg). The tongue exhibits a crimped/bitten section near its base, suggesting the presence of a predator.

There are at least 250 individuals, comprising approximately 12 swarm events present in the multi-phase dolichopodidae swarm. The Acropyga queen ant carrying a mealy bug is only the fourth reported example of this highly specialized event. Intricate details of both specimens are easily seen, including the three delicate filaments at the end of the mealy bug’s abdomen.