r/FossilPorn

RARE Extinct "Iron-maiden Ant" (Zigrasimecia) in Burmese Burmite amber fossil

*From My Personal Collection of Hymenoptera*

Age: 99 Million Years Ago

Order: Hymenoptera

Family: Formicidae

Subfamily: Zigrasimeciinae (Extinct Stem-Group Ant)

Genus: Zigrasimecia

Species: (Inconclusive)

Other notable inclusions:

Zigrasimecia, popularly known as the "iron maiden ant," is an extinct genus of highly specialized stem-group ants that lived during the Cretaceous period, roughly 98 to 99 million years ago. It belongs to the unique subfamily Zigrasimeciinae. Fossils of this genus are found almost exclusively as inclusions in Burmese (Kachin) amber within Myanmar.

- Their highly specialized jaws swung open sideways (posterolaterally) and snapped shut backward (anteromedially). The inner oral face of the mandibles was covered in spiky, traction-strengthening hairs (setae).

- Paleontologists believe Zigrasimecia was a generalist predator. It frequently shared its terrestrial environment and likely engaged in violent resource conflicts with Gerontoformica, another genus of ancient Cretaceous ants.

- Because their specialized mandibles were optimized strictly for combat and trapping, scientists hypothesize that the rugose, hardened cuticular projections on their crowns were utilized to dig out nests.

*This particular specimen which measures about 2.9mm (unstretched) is exceptionally preserved and is contained in a very clear yellow amber stone.*

*From My Personal Collection of Hymenoptera*

A little cluster of Dactylioceras semicelatum I finished preparing this morning.

Three ammonite genus visible and goodness knows what else. Lengthy prep required!

RARE Extinct Spongefly (Paradoxosisyrinae) in Burmese Burmite amber fossil

Age: 99 Million Years Ago

Order: Neuroptera

Family: Sisyridae

Subfamily: Paradoxosisyrinae (Extinct Spongefly)

Genus: Paradoxosisyra

Species: (Inconclusive)

Other notable inclusions: a Piddock boring, botanical matter and a Beetle also in the piece.

Paradoxosisyrinae is an extinct subfamily of Spongeflies (in the family Sisyridae) known from Cretaceous fossils, notably discovered in 99-million-year-old Burmese amber. These tiny, specialized lacewings feature extraordinarily long mouthparts, pointing to ancient feeding strategies like nectarivory or probing shallow Cretaceous flowers.

Paradoxosisyrinae represent the earliest known lineage of Spongeflies, dating back to the Cenomanian stage of the Cretaceous period.

Instead of the aquatic, sponge-feeding habits of modern subfamilies, these Cretaceous stem-group Spongeflies were likely adapted to feed on nectar from early shallow flowers.

Age: 99 Million Years Ago

RARE Possible Frog Tadpoles in Burmese Burmite amber fossil

There have not been any tadpoles found yet in the fossil record of amber. While adult and juvenile forest frogs like Electrorana limoae have been found in 99-million-year-old Burmese amber from Myanmar, fully aquatic life stages like tadpoles are almost impossible to trap in tree resin, making them infinitely rarer than adult frogs.

- *These particular specimens appear to be an extremely rare case of tadpole hatchlings preserved in Burmese amber.
The specimens each measure about 2.5mm to 3mm in length. There are about eight to nine tadpole hatchlings in this piece (three of them are badly preserved and have degraded).*

- I cannot know the exact species or type of frog that these tadpole hatchlings are associated with but it is quite possible that these belong to a type of tropical tree frog (similar to modern tree frogs) which are known to lay eggs on top of leaves that hang over puddles of water.

- *In this extraordinary piece of amber, there is also what appears to be imprints of a leaf in the background layers of the amber along with two notable enhydros (trapped pockets of water). There is some loose debris that moves inside one enhydro (left enhydro) as well as some strange small spherical occlusions.*

Other notable inclusions: strange loose debris contained in the left enhydro (which moves when the amber is tilted), many unknown tiny filaments scattered in the piece next to the tadpole hatchlings and two strange spherical occlusions.

context: Cretaceous limestones