Editing Cretaceous (section)

== Flora ==
[[File:Archaefructus_liaoningensis.jpg|thumb|Facsimile of a fossil of ''Archaefructus'' from the Yixian Formation, China]]
[[File:Jaguariba wiersemana, Brazil - Museum fur Naturkunde, Berlin - MB. Pb. 1999-614.jpg|thumb|right|Fossil ''[[Jaguariba wiersemana]]'' specimen in the collection of the [[Natural History Museum, Berlin]], Germany]]
{{main|Cretaceous Terrestrial Revolution}}
[[Flowering plant]]s (angiosperms) make up around 90% of living plant species today. Prior to the rise of angiosperms, during the Jurassic and the Early Cretaceous, the higher flora was dominated by [[gymnosperm]] groups, including [[cycad]]s, [[Pinophyta|conifers]], [[ginkgophyte]]s, [[Gnetophyta|gnetophytes]] and close relatives, as well as the extinct [[Bennettitales]]. Other groups of plants included [[Pteridospermatophyta|pteridosperms]] or "seed ferns", a collective term that refers to disparate groups of extinct seed plants with fern-like foliage, including groups such as [[Corystospermaceae]] and [[Caytoniales]]. The exact origins of angiosperms are uncertain, although molecular evidence suggests that they are not closely related to any living group of gymnosperms.<ref name="Coiro-2019" />

The earliest widely accepted evidence of flowering plants are monosulcate (single-grooved) [[pollen]] grains from the late [[Valanginian]] (~ 134 million years ago) found in Israel<ref>{{cite book |last1=Brenner |first1=G.J. |title=Flowering Plant Origin, Evolution & Phylogeny |chapter=Evidence for the Earliest Stage of Angiosperm Pollen Evolution: A Paleoequatorial Section from Israel |editor1-last=Taylor |editor1-first=D.W. |editor2-last=Hickey |editor2-first=L.J. |date=1996 |isbn=978-0-585-23095-5 |pages=91–115 |location=New York |publisher=Chapman & Hall |doi=10.1007/978-0-585-23095-5_5}}</ref> and Italy,<ref>Trevisan L. 1988. Angiospermous pollen (monosulcate–trichotomosulcate phase) from the very early Lower Cretaceous of southern Tuscany (Italy): some aspects. 7th International Palynological Congress Abstracts Volume. Brisbane, Australia: University of Queensland, 165.</ref> initially at low abundance. [[Molecular clock]] estimates conflict with fossil estimates, suggesting the diversification of [[Crown group|crown-group]] angiosperms during the Late Triassic or the Jurassic, but such estimates are difficult to reconcile with the heavily sampled pollen record and the distinctive tricolpate to tricolporoidate (triple grooved) pollen of [[Eudicots|eudicot]] angiosperms.<ref name="Coiro-2019">{{Cite journal|last1=Coiro|first1=Mario|last2=Doyle|first2=James A.|last3=Hilton|first3=Jason|date=July 2019|title=How deep is the conflict between molecular and fossil evidence on the age of angiosperms?|journal=New Phytologist|language=en|volume=223|issue=1|pages=83–99|doi=10.1111/nph.15708|pmid=30681148|issn=0028-646X|doi-access=free}}</ref> Among the oldest records of Angiosperm [[macrofossil]]s are ''[[Montsechia]]'' from the [[Barremian]] aged [[La Huérguina Formation|Las Hoyas]] beds of Spain and ''[[Archaefructus]]'' from the Barremian-Aptian boundary [[Yixian Formation]] in China. Tricolpate pollen distinctive of eudicots first appears in the Late Barremian, while the earliest remains of [[monocots]] are known from the [[Aptian]].<ref name="Coiro-2019" /> Flowering plants underwent a rapid radiation beginning during the middle Cretaceous, becoming the dominant group of land plants by the end of the period, coincident with the decline of previously dominant groups such as conifers.<ref>{{Cite journal|last1=Condamine|first1=Fabien L.|last2=Silvestro|first2=Daniele|last3=Koppelhus|first3=Eva B.|last4=Antonelli|first4=Alexandre|date=2020-11-17|title=The rise of angiosperms pushed conifers to decline during global cooling|journal=[[Proceedings of the National Academy of Sciences of the United States of America]]|language=en|volume=117|issue=46|pages=28867–28875|doi=10.1073/pnas.2005571117|issn=0027-8424|pmc=7682372|pmid=33139543|bibcode=2020PNAS..11728867C |doi-access=free }}</ref> The oldest known fossils of [[Poaceae|grasses]] are from the [[Albian]],<ref>{{Cite journal|last1=Wu|first1=Yan|last2=You|first2=Hai-Lu|last3=Li|first3=Xiao-Qiang|date=2018-09-01|title=Dinosaur-associated Poaceae epidermis and phytoliths from the Early Cretaceous of China|url=https://academic.oup.com/nsr/article/5/5/721/4769666|journal=National Science Review|language=en|volume=5|issue=5|pages=721–727|doi=10.1093/nsr/nwx145|issn=2095-5138|doi-access=free}}</ref> with the family having diversified into modern groups by the end of the Cretaceous.<ref>{{Cite journal|last1=Prasad|first1=V.|last2=Strömberg|first2=C. a. E.|last3=Leaché|first3=A. D.|last4=Samant|first4=B.|last5=Patnaik|first5=R.|last6=Tang|first6=L.|last7=Mohabey|first7=D. M.|last8=Ge|first8=S.|last9=Sahni|first9=A.|date=2011-09-20|title=Late Cretaceous origin of the rice tribe provides evidence for early diversification in Poaceae|journal=[[Nature Communications]]|language=en|volume=2|issue=1|pages=480|doi=10.1038/ncomms1482|pmid=21934664|bibcode=2011NatCo...2..480P|issn=2041-1723|doi-access=free}}</ref> The oldest large angiosperm trees are known from the [[Turonian]] (c. 90 Mya) of New Jersey, with the trunk having a preserved diameter of {{convert|1.8|m|ft}} and an estimated height of {{convert|50|m|ft}}.<ref>{{Cite journal|last1=Jud|first1=Nathan A.|last2=D’Emic|first2=Michael D.|last3=Williams|first3=Scott A.|last4=Mathews|first4=Josh C.|last5=Tremaine|first5=Katie M.|last6=Bhattacharya|first6=Janok|date=September 2018|title=A new fossil assemblage shows that large angiosperm trees grew in North America by the Turonian (Late Cretaceous)|url= |journal=[[Science Advances]]|language=en|volume=4|issue=9|pages=eaar8568|doi=10.1126/sciadv.aar8568|issn=2375-2548|pmc=6157959|pmid=30263954|bibcode=2018SciA....4.8568J}}</ref>

During the Cretaceous, [[fern]]s in the order [[Polypodiales]], which make up 80% of living fern species, would also begin to diversify.<ref>{{Cite journal|last1=Regalado|first1=Ledis|last2=Schmidt|first2=Alexander R.|last3=Müller|first3=Patrick|last4=Niedermeier|first4=Lisa|last5=Krings|first5=Michael|last6=Schneider|first6=Harald|date=July 2019|title=Heinrichsia cheilanthoides gen. et sp. nov., a fossil fern in the family Pteridaceae (Polypodiales) from the Cretaceous amber forests of Myanmar|journal=[[Journal of Systematics and Evolution]]|language=en|volume=57|issue=4|pages=329–338|doi=10.1111/jse.12514|issn=1674-4918|doi-access=free}}</ref>