This has been a banner year for avocados in Ventura County, with the tonnage likely to set a local record. Other avocado growing regions in California are also producing well, thanks to good weather last year when the trees were flowering and setting this year's fruit.

Next time you buy an avocado, take a moment to heft that fruit in your hand and wonder how on earth something so strange could evolve in nature.

There are three families of avocados -- one originating in Mexico, another in the West Indies and the third in Guatemala -- and without some means of seed dispersal, they all would have a heck of a time reproducing. In the wild, avocado trees grow scattered throughout dense tropical forests, and a thick layer of dead leaves accumulates beneath their branches. Fruit that simply drops to the ground beneath a wild tree has little chance of germinating because of the deep shade and inaccessible soil. So what accounts for the avocados' wide dispersal and reproductive success?

Trickery, according to ecologists.

Botanically, avocados are berries. Plants produce berries as a reproductive strategy, surrounding their seeds with a fleshy, nutritious pulp that entices more mobile life forms to gobble the entire package and wander off before excreting the durable germ of the next generation. It's a strategy plants have evolved to ensure their offspring won't compete with them for light, water and nutrients.

It's easy to imagine how this works for blackberries, blueberries and other fruits small enough to be ingested whole by birds, bats, bears and other familiar creatures. But heft an avocado, and try to imagine what would swallow such a thing in its entirety. Bear in mind that the half-pound Hass avocados commonly sold in supermarkets are rather small by global avocado standards; many of the nearly 1,000 named varieties produce fruit that typically is three times as large.

In 1982, university professors Daniel Jantzen and Paul Martin published an intriguing article in the journal Science hypothesizing that several groups of Mesoamerican trees and shrubs with giant fruits are what they termed "neotropical anachronisms" -- plants that evolved in concert with jumbo herbivores, which have since vanished.

The prehistoric megafauna of Mesoamerica included horses, giant ground sloths and lumbering creatures known as gomphotheres (View image), which were related and similar in appearance to mastodons, mammoths and modern elephants. All were big enough to swallow and disperse the seeds of avocados, forest palms and other trees with huge fruit.

Those big critters all disappeared about 10,000 years ago, but ecologists believe that some of the plants that evolved to take advantage of the animals' gargantuan guts persist today, their oversize fruit a sort of ghostly evolutionary leftover.

So, eat an avocado and imagine an elephant. Or something like it.