Editing Phanerozoic (section)

====Cretaceous Period====
{{Main|Cretaceous}}
The Cretaceous is the Phanerozoic's longest period and the last period of the Mesozoic.  It spans from 145 million to 66&nbsp;million years ago, and is divided into two epochs: [[Early Cretaceous]], and [[Late Cretaceous]].<ref name="Carl Fred Koch">{{cite encyclopedia|url=http://www.britannica.com/EBchecked/topic/142729/Cretaceous-Period/257709/Major-subdivisions-of-the-Cretaceous-System|title=Cretaceous|author=Carl Fred Koch|encyclopedia=Old Dominion University|url-status=live|archive-url=https://web.archive.org/web/20150514211348/http://www.britannica.com/EBchecked/topic/142729/Cretaceous-Period/257709/Major-subdivisions-of-the-Cretaceous-System|archive-date=14 May 2015}}</ref>

[[File:Tylosaurus-proriger.jpg|thumb|294x294px|''[[Tylosaurus]]'', a type of large marine lizards known as [[mosasaur]]s]]
The Early Cretaceous Epoch spans from 145 million to 100&nbsp;million years ago.<ref name="Carl Fred Koch"/> Dinosaurs continued to be abundant, with groups such as [[tyrannosauroid]]s, [[Avialae|avialans]] ([[bird]]s), [[marginocephalia]]ns, and [[ornithopod]]s seeing early glimpses of later success. Other tetrapods, such as [[stegosaur]]s and ichthyosaurs, declined significantly, and sauropods were restricted to southern continents.

The Late Cretaceous Epoch spans from 100 million to 66&nbsp;million years ago.<ref name="Carl Fred Koch"/> The Late Cretaceous featured a cooling trend that would continue into the [[Cenozoic]] Era. Eventually, the tropical climate was restricted to the equator and areas beyond the tropic lines featured more seasonal climates. Dinosaurs still thrived as new species such as ''[[Tyrannosaurus]]'', ''[[Ankylosaurus]]'', ''[[Triceratops]]'' and [[hadrosaurs]] dominated the food web. Whether or not [[pterosaur]]s went into a decline as birds radiated is debated; however, many families survived until the end of the Cretaceous, alongside new forms such as the gigantic ''[[Quetzalcoatlus]]''.<ref>{{Cite news|url=https://blog.everythingdinosaur.co.uk/blog/_archives/2018/03/15/pterosaurs-more-diverse-at-the-end-of-the-cretaceous-than-previously-thought.html|title=Pterosaurs More Diverse at the End of the Cretaceous than Previously Thought|work=Everything Dinosaur Blog|access-date=14 August 2018|language=en-US|archive-date=27 September 2020|archive-url=https://web.archive.org/web/20200927102331/https://blog.everythingdinosaur.co.uk/blog/_archives/2018/03/15/pterosaurs-more-diverse-at-the-end-of-the-cretaceous-than-previously-thought.html|url-status=live}}</ref> Mammals diversified despite their small sizes, with [[metatheria]]ns ([[marsupial]]s and kin) and [[eutheria]]ns ([[Placentalia|placentals]] and kin) coming into their own. In the oceans, [[mosasaurs]] diversified to fill the role of the now-extinct ichthyosaurs, alongside huge plesiosaurs such as ''[[Elasmosaurus]]''. Also, the first flowering plants evolved. At the end of the Cretaceous, the [[Deccan Traps]] and other volcanic eruptions were poisoning the atmosphere. As this was continued, it is thought that a large [[meteor]] smashed into Earth, creating the [[Chicxulub Crater]] and causing the event known as the [[Cretaceous–Paleogene extinction event|K–Pg extinction]], the fifth and most recent mass extinction event, during which 75% of life on Earth became extinct, including all non-avian dinosaurs. Every living thing with a body mass over 10 kilograms became extinct, and the Age of Dinosaurs came to an end.<ref>{{cite web|url=http://www.ucmp.berkeley.edu/mesozoic/cretaceous/cretaceous.php|title=Cretaceous|author=University of California|work=University of California|url-status=live|archive-url=https://web.archive.org/web/20170611021416/http://www.ucmp.berkeley.edu/mesozoic/cretaceous/cretaceous.php|archive-date=11 June 2017}}</ref><ref>{{cite web|url=http://www.universetoday.com/36697/the-asteroid-that-killed-the-dinosaurs/|title=K-T Extinction event|author=Elizabeth Howell|work=Universe Today|date=3 February 2015|url-status=live|archive-url=https://web.archive.org/web/20150505160632/http://www.universetoday.com/36697/the-asteroid-that-killed-the-dinosaurs/|archive-date=5 May 2015}}</ref>