When the meteor hit Mexico, Why were Dinosaurs on the other side of the world affected say China or Australia ?
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Across the entire globe exists the K-Pg Boundary (formerly known as the KT boundary). Beneath it, one finds dino fossils. Above it, no dino fossils (specifically non-avian dinos). The actual boundary is quite visible, tons of pictures of it online. It’s a band of concentrated iridium, suggesting a massive impact event – like the Chicxulub Crater.
The immediate effects of such an impact would have resulted in earthquakes, tsunamis, firestorms (and thus forest fires) that would have immediately killed off several unsheltered surface-dwelling organisms. There’s debate about how rapidly the extinction event came about, whether there was a global fireball from an (admittedly MASSIVE) impact event or a slower event due to abrupt climate change from all the matter that a massive impact would toss into the atmosphere.
There’s two other factors to keep in mind that eludes a lot of people when discussing the K-Pg extinction: Most importantly for terrestrial (land) organisms is that all the land on the planet was more concentrated – as in all the land was closer together. Not quite Pangea, but the continents weren’t as spread out as they are today. There was also less land due to the higher temperatures of the period, hence smaller amounts of water trapped in the ice caps and glaciers, so ocean levels were higher (it’s why we sometimes find marine fossiles far inland and even on mountains!) The other thing is that there are volcanoes in modern India that were erupting *at the same time* and really delivered a one-two knockout punch for the dinos in terms of that abrupt climate change.
In short, big meteroite and big volcanoes + smaller land = dead dinos. Continental shift + geological process = dinos on “other side of the world” being dead, too.
Of course, this is our best guess. But it’s a guess that has loads of geological evidence behind it.
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