The Lagonomegopidae spider family is now extinct, but spiders have a long history and first appeared in the Carboniferous, between 359 and 299 million years ago.
One “shows a female lagonomegopid spider clutching an egg sac containing eggs about to hatch (you can see the pre-hatched cubs in the egg sac),” the author said. study Paul Selden, Gulf-Hedberg Emeritus Professor Emeritus at the University of Kansas. , in an email. “This is exactly what a live female spider would look like nestled in a crevice in the bark of a tree (in this case, just before being inundated with tree resin). “
Other pieces of amber show a group of tiny spiders that had just hatched. This shows that a female lagoonomegopid spider protected her egg sac from damage. Once the spiders hatched, they stayed together and were kept by their mother, as evidenced by the leg fragments of Lagonomegopidae from the same piece of amber.
This suggests that baby spiders likely stayed close to their mothers for some time after birth.
The researchers were pleasantly surprised by “how perfectly everything fell into place.” We had about three specimens that all corroborated each other in the story, ”Selden said.
The researchers used CT scans to spot tiny eyes and other features that revealed the spider’s identity as well as the tiny spiders in 3D detail.
Lagonomegopidae spiders are distinguished by their large pair of eyes located at the front corners of the head. Other known fossils of these spiders revealed that they had reflective tapetum in their eyes, similar to other nocturnal creatures – think how a cat’s eyes blink in the dark.
These now extinct spiders look like modern jumping spiders, but they are not related at all.
Spiders are known for their maternal care, but fossilized examples of this are extremely rare.
“While we expected spiders to have maternal instincts from the start, it’s nonetheless very nice to have actual physical evidence from the fossil record around 100 million years ago,” Selden said.
But what does maternal care really mean, as can be seen in many species of spiders living today?
“Parental care refers to any investment by the parent that improves the fitness of their offspring, and often at the expense of the parent’s survival and future reproduction,” the researchers wrote in the study. “Its evolution represents a breakthrough in the adaptation of animals to their environment and has important implications for the evolution of sociability. “
Other arthropods that exhibit this type of care include insects and crustaceans.
Selden and his colleagues will continue to research “other examples of behavior frozen in time.”