The fallen include Homasi, also known as Grootboom, a giant tree in Namibia. The circumference of a mature tree's trunk can reach 20 metres, and a tree normally lives for about 500 years, though experts estimate some to be as old as 5,000 years. In November 2017, heavy rainfall triggered rot that took it down.
The bar's owners blamed rot caused by heavy rain and threw a barbeque to honor its passing.
Some of the largest trees have died over the last 12 years.
Man-made climate change is a likely suspect, scientists said.
The researchers set out to date the trees, but discovered that they were dying in an "event of unprecedented magnitude", they write. "It's statistically very unlikely". Of these, a group of around two dozen stood out for their exceptional size and, or, age.
The iconic trees can reach almost 2,000 years of age.
Baobabs are notoriously tricky to date because their odd shape and growth patterns can complicate traditional tree-ring analysis - and Patrut's method drew some controversy from other baobab ecologists.
Pretty much every baobab tree in Southern Africa is covered in the healed scars of past elephant attacks, which speaks to the trees awesome fix ability, said David Baum, a University of Wisconsin botanist who is familiar with the new study and contributed to a recent Biodiversity International publication cataloguing the trees attributes, in an email.
Several of southern Africa's largest baobab trees have suddenly and unexpectedly died, and scientists fear climate change is the culprit. The increased temperature and drought are the major threats, says Patrut.
According to the Kruger Park, baobabs are "very hard to kill".
The latest survey of ancient baobabs suggests climate change may already be affecting the continent's vegetation.
Baobabs have deep cultural significance for many communities across southern Africa.
Baobabs have a characteristic trunk with a massive girth and only branch at a particular height from the ground.
The trees also support wildlife; they are important nesting sites for birds.
The baobab is the biggest and longest-living flowering tree. In 2011, the oldest known specimen that sprouted about 2450 years ago-died and toppled over.
But baobab dating is a tricky, controversial process.
The iconic tree can live to be 3,000 years old, according to the website of the Kruger National Park in South Africa, a natural baobab habitat.
The problem is the tree's so-called "architecture". They have been surveying the trees since 2005 and have developed a theory of how they grow, while also documenting the losses.
In a typical tree ring, it's easy to trace a straight line from the oldest part at the center to the youngest part at the edge. People have used the tree for centuries as a source of food, medicine, shelter and even to make clothes.
But according to Patrut, the big central hollows were never filled with wood, and are instead the result of independent trunks fusing over time with a gap in the middle - "the only reasonable explanation", he says.
Their findings were published in the Nature Plants journal on June 11. Many of these unusual trees have started dying suddenly. But it matters because correctly identifying the oldest part of a tree is a prerequisite for knowing its age. If there isn't enough water in their system when they produce their leaves, flowers and fruit, the tree will die quickly and collapse.
But Baum does not contest that large baobabs are dying - something he calls heartbreaking..