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Ancestor: Nicrophorus americanus (American Burying Beetle)

Size: Varies between 1 cm and 4 cm, depending on species.

Dietary Needs: Larvae depend on decaying meat, partly digested by their parents at first few days of life. Can't be too fresh. Adults sometimes eat other invertebrates that they cross paths with, but they  also would rather eat vertebrate meat at any stage of freshness.

Life Cycle: Larvae are now born within the pit in the corpse formed by their parents, not in the soil as their ancestors were. They are also more reliant on pre-digestion of meat by their parents for the first few days. Aside from their own parents they are raised by all parents of all larvae on the corpse fairly equally. Communal parents are more scrupulous cullers, having no bias for or against even their own young, only against the weak or sick. The surviving offspring grow quickly.

When they're large enough they will crawl into the soil beneath the corpse and pupate into an adult. They are able to delay emergence into an adult until the soil is wet, so that they don't emerge in the midst of a dry season.

A newly emerged adult is able to survive on small invertebrate prey but their life goal is to find a large corpse with other communal buriers. One way they find a corpse is by chemoreception, but this might not work if they are upwind. Another way is that the first beetle to discover a corpse makes a loud, low-pitched buzzing sounds and pulse-like clicks in an alternating rhythm, by clapping their abdomen and elytra via convulsive vibrations. The elytra is enlarged with a hollow space between it and the abdomen, and acts as a resonance chamber, amplifying the sounds and giving them more bass. The audio pulses from these sounds are quite loud and carry far. Burying beetles could not hear, but the communal burier is able to feel the pulses inside their bodies via the surface of their elytra from another beetle producing the sound a few hundred metres away.

They aren't able to determine direction and have to land frequently to detect if they are "hot" or "cold" from the source. It also has less effective range than smell, but is a fall-back to give the beetles another chance to detect the corpse if smell is travelling the wrong way.

The reasons why the first beetle attracts more beetles is that  firstly, they need to attract a mate. Secondly these beetles are formidable in numbers, using their large powerful jaws they can collectively overwhelm predators and scavengers much larger than themselves. Once enough beetles converge on a corpse it is effectively claimed by them.

There is still an initial competition between adults for space in a carcass once the corpse is claimed, with losers killed or driven out. But once the beetles have paired up and started laying eggs in excavated pits in the corpse, the adults start mellowing out. They mix body fluids (beetle kisses) so that they develop a unique shared combined scent. Any beetle that later approaches lacking this scent, the resident adults drive them out or kill them.

The combined number of beetles makes concealing the corpse easier than their ancestors when it was just a pair working together. Together they bury it under a mound of mostly dirt (or whichever available substrate) and some leaves and twigs small enough for them to carry. They don't always do a perfect job, especially with the largest animals. But even a thin covering of dirt can dampen the smell considerably.

They don't just raise their own brood, they contribute to raising all larvae of the same species in the carcass. This means that if a parent dies defending the carcass, their own brood will still be cared for by multiple adults. And in defending the carcass, they improved the survival chances of the other beetle's offspring too. There is a mutual benefit amongst all in the community to act selflessly when the whole community is in danger.

Other: Although small, their bite is dangerous for larger animals. Not only can their jaws take out small chunks of flesh they also leave behind many kinds of bacteria and other microbes from the corpse in the wound. So even if the threatening animal learns it's lesson it might still die later which is another win for the beetle species - that corpse might be their offspring's home later. 

The loud buzzing they use to attract other beetles can also sometimes intimidate threatening animals. During a beetle attack on a larger animal this buzzing can be heard loudly from the horde.