A US-backed alliance of Syrian fighters announced that the jihadist group Islamic State (IS) has lost the last pocket of territory in Syria it controlled, bringing a formal end to the "caliphate" it proclaimed in 2014. IS once controlled 88,000 sq km (34,000 sq miles) of territory stretching from western Syria to eastern Iraq.

It imposed its brutal rule on almost eight million people, generating billions of dollars in revenue from oil, extortion, robbery and kidnapping. Despite the demise of its physical caliphate, IS remains a battle-hardened and well-disciplined force whose "enduring defeat" is not assured.

The head of the US military's Central Command, Gen Joseph Votel, said in February that it was necessary to maintain "a vigilant offensive against the now largely dispersed and disaggregated [IS] that retains leaders, fighters, facilitators, resources and the profane ideology that fuels their efforts".

Scientists said they have discovered a "stunning" trove of thousands of fossils on a river bank in China. The fossils are estimated to be about 518 million years old, and are particularly unusual because the soft body tissue of many creatures, including their skin, eyes, and internal organs, have been "exquisitely" well preserved.

Palaeontologists have called the findings "mind-blowing" - especially because more than half the fossils are previously undiscovered species. The fossils, known as the Qingjiang biota, were collected near Danshui river in Hubei province. More than 20,000 specimens were collected, and a total of 4,351 have been analysed so far, including worms, jellyfish, sea anemones and algae. They will become a "very important source in the study of the early origins of creatures", one of the fieldwork leaders, Prof Xingliang Zhang from China's Northwest University, told the BBC.

An exit poll in Thailand's first election since a 2014 coup indicated the ousted Pheu Thai Party of exiled former premier Thaksin Shinawatra won the most seats at 163, while the military proxy party Palang Pracharat came second at 96 seats. But unofficial results direct from the Election Commission (EC) gave Pheu Thai fewer votes, with Palang Pracharat winning a surprising number of seats in the former Pheu Thai stronghold of northern Thailand.

Either projection would mean that Pheu Thai would lack sufficient votes to form a majority government in its hoped-for "democratic front" with other parties. The "pro-democracy" parties would need a combined 376 seats in the 500-member House to form a government if all 250 junta-appointed senators, as expected, support PPRP and the other parties that favour the military. The early signs are that a PPRP-led coalition could take power.

Special counsel Robert Mueller found no evidence President Donald Trump's campaign "conspired or coordinated" with Russia to influence the 2016 presidential election but reached no conclusion on whether Trump obstructed justice. That brought a hearty claim of vindication from Trump but set the stage for new rounds of political and legal fighting. Mueller's conclusions, summarized by Barr in a four page letter to Congress, represented a victory for Trump on a key question that has hung over his presidency from the start - whether his campaign worked with Russia to defeat Democrat Hillary Clinton.

Democrats pointed out that Mueller found evidence for and against obstruction and demanded to see his full report. They insisted that even the summary by the president's attorney general hardly put him in the clear.