Editing Poaceae (section)

=== Evolutionary history ===
Grasses include some of the most versatile [[plant life-form]]s. They became widespread toward the end of the [[Cretaceous]] period, and fossilized [[dinosaur]] dung ([[coprolite]]s) belonging to the [[Sauropoda|sauropod]] [[Titanosauria|titanosaurs]] (though this provenance has been questioned)<ref name=":0">{{Cite journal |last1=Khosla |first1=Ashu |last2=Chin |first2=Karen |last3=Verma |first3=Omkar |last4=Lucas |first4=Spencer G. |last5=Hunt |first5=Adrian P. |last6=Xi |first6=Dangpeng |last7=Dutta |first7=Debi |last8=Alimohammadian |first8=Habib |date=2025-03-14 |title=Palaeoenvironmental and palaeoecological inferences from inclusions in vertebrate omnivore coprolites from the Upper Cretaceous Lameta Formation of central India |url=https://linkinghub.elsevier.com/retrieve/pii/S0195667125000333 |journal=Cretaceous Research |volume=172 |language=en |pages=106110 |doi=10.1016/j.cretres.2025.106110|bibcode=2025CrRes.17206110K }}</ref> have been found containing [[phytolith]]s of a variety that include grasses that are related to modern [[rice]] and [[bamboo]].<ref>{{cite journal |title=Dinosaurs Dined on Grass |first1=Dolores R. |last1=Piperno |first2=Hans-Dieter |last2=Sues |journal=[[Science (magazine)|Science]] |date=18 November 2005 |volume=310 |issue=5751 |pages=1126–1128 |doi=10.1126/science.1121020 |pmid=16293745|s2cid=83493897 }}</ref> Grasses have adapted to conditions in lush [[rain forest]]s, dry [[desert]]s, cold mountains and even [[Intertidal ecology|intertidal habitat]]s, and are currently the most widespread plant type; grass is a valuable source of food and energy for all sorts of wildlife.

A cladogram shows subfamilies and approximate species numbers in brackets:<ref name="GPWGII-2012">{{cite journal |author=Grass Phylogeny Working Group II |date=2012 |title=New grass phylogeny resolves deep evolutionary relationships and discovers C<sub>4</sub> origins |journal=New Phytologist |volume=193 |issue=2 |pages=304–312 |doi=10.1111/j.1469-8137.2011.03972.x |pmid=22115274|bibcode=2012NewPh.193..304. |hdl=2262/73271 |hdl-access=free }} {{open access}}</ref>

{{clade|style=font-size:90%;line-height:75%;width:800px;
    |label1=
|1={{clade
  |1={{clade
    |1={{clade
      |1={{clade
      |label1=[[PACMAD clade]]
      |1={{clade
  |1={{clade
       |1={{clade
      |1={{clade
    |1=[[Chloridoideae]] (1600)
    |2=[[Danthonioideae]] (300)
         }}
      |2={{clade
    |1=[[Micrairoideae]] (200)
    |2=[[Arundinoideae]] (50)
         }}
   }}
       |2=[[Panicoideae]] (3250)
     }}
  |2=[[Aristidoideae]] (350)
         }}
      |label2=[[BOP clade]]
      |2={{clade
            |1=[[Oryzoideae]] (110)
            |2={{clade
          |1=[[Bambusoideae]] – bamboos (1450)
          |2=[[Pooideae]] (3850)
        }}
         }}
         }}
      |2=[[Puelioideae]] (11)
       }}
    |2=[[Pharoideae]] (13)
     }}
  |2=[[Anomochlooideae]] (4)
  }}
}}

[[File:Anomochloa.jpg|thumb|Drawing of ''[[Anomochloa marantoidea]]'', one of the most primitive living grass species]]

Before 2005, fossil findings indicated that grasses evolved around 55 million years ago. Finds of grass-like [[phytolith]]s in [[Cretaceous]] dinosaur [[coprolite]]s from the latest Cretaceous ([[Maastrichtian]]) aged [[Lameta Formation]] of India have pushed this date back to 66 million years ago.<ref name="Piperno-2005">{{cite journal
 | last1 = Piperno
 | first1 = Dolores R.
 | last2 = Sues
 | first2 = Hans-Dieter
 | date = 2005
 | title = Dinosaurs Dined on Grass
 | journal = Science
 | volume = 310
 | issue = 5751
 | pages = 1126–8
 | doi = 10.1126/science.1121020
 | pmid = 16293745
| s2cid = 83493897
 }}</ref><ref name="Prasad-2005">{{cite journal
 | last1= Prasad |first1=V. |last2=Stroemberg |first2=C.A.E. |last3=Alimohammadian |first3=H. |last4=Sahni |first4=A.
 | date = 2005
 | title = Dinosaur coprolites and the early evolution of grasses and grazers
 | journal = Science
 | volume = 310
 | issue = 5751
 | pages = 1177–1180
 | doi=10.1126/science.1118806
 | pmid = 16293759
|bibcode=2005Sci...310.1177P |s2cid=1816461 }}</ref> Due to high [[Phosphorus#Nutrition|phosphatic]] content of 12.2-16.2% in Type A coprolites collected from the Lameta, an omnivore is hypothesized to be the source, contradicting the hypothesis of a sauropod origin.<ref name=":0" /> In 2011, fossils from the same deposit were found to belong to the modern rice tribe [[Oryzeae]], suggesting substantial diversification of major lineages by this time.<ref name="Prasad-2011">{{cite journal |last1=Prasad |first1=V. |last2=Strömberg |first2=C.A. |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 |title=Late Cretaceous origin of the rice tribe provides evidence for early diversification in Poaceae |journal=Nature Communications |volume=2 |page=480 |doi=10.1038/ncomms1482 |pmid=21934664 |bibcode=2011NatCo...2..480P |doi-access=free }}</ref>

In 2018, a study described grass microfossils extracted from the teeth of the [[Hadrosauroidea|hadrosauroid]] [[dinosaur]] ''[[Equijubus]] normani'' from northern China, dating to the [[Albian]] stage of the [[Early Cretaceous]] approximately 113–100 million years ago, which were found to belong to primitive lineages within Poaceae, similar in position to the Anomochlooideae. These are currently the oldest known grass fossils.<ref name="Yan-2018" />

Fossils of ''Phragmites'' have been found in the Late Cretaceous of North America, particularly in the Maastrichtian aged [[Laramie Formation]].<ref>{{cite web |title=Mount Everts (Cretaceous of the United States) |url=https://paleobiodb.org/classic/basicCollectionSearch?collection_no=35576 |website=PBDB.org}}</ref> However slightly older fossils of 	
''Phragmites'' have been found in the Eastern coast of the US dating the [[Campanian]] (such as in the [[Black Creek Formation]]). <ref>{{cite journal |last1=Berry |first1=E. W. |title=The Upper Cretaceous and Eocene floras of South Carolina and Georgia |journal=U.S. Geological Survey Professional Paper |date=1914 |volume=84 |page=11 |doi=10.3133/pp84|bibcode=1914usgs.rept...11B }}</ref>

The relationships among the three subfamilies Bambusoideae, Oryzoideae and Pooideae in the BOP clade have been resolved: Bambusoideae and Pooideae are more closely related to each other than to Oryzoideae.<ref name="Wu-2012">{{cite journal|last1=Wu |first1=Z.Q. |last2=Ge |first2=S. |date=2012 |title=The phylogeny of the BEP clade in grasses revisited: Evidence from the whole-genome sequences of chloroplasts |journal=Molecular Phylogenetics and Evolution|volume=62 |issue=1 |pages=573–578 |doi=10.1016/j.ympev.2011.10.019 |pmid=22093967 |bibcode=2012MolPE..62..573W }}</ref> This separation occurred within the relatively short time span of about 4 million years.

According to [[Lester Charles King]], the spread of grasses in the [[Neogene|Late Cenozoic]] would have changed patterns of [[hillslope evolution]] favouring slopes that are convex upslope and concave downslope and lacking a [[escarpment|free face]] were common. King argued that this was the result of more slowly acting surface wash caused by carpets of grass which in turn would have resulted in relatively more [[downhill creep|soil creep]].<ref name="Twidale-1992">{{Citation
 | last1  = Twidale
 | first1 = C.R.
 |author-link=Charles Rowland Twidale
 | title = King of the plains: Lester King's contributions to geomorphology
 | journal = [[Geomorphology (journal)|Geomorphology]]
 | volume  = 5
 | issue   =6
 | year    = 1992
 | pages   = 491–509
| doi = 10.1016/0169-555X(92)90021-F
 | bibcode = 1992Geomo...5..491T
 }}</ref><ref name="King-1953">{{cite journal |last1=King |first1=L.C. |date=1953 |title=Canons of landscape evolution |journal=Geological Society of America Bulletin |volume=64 |issue=7 |pages=721–752 |doi= 10.1130/0016-7606(1953)64[721:COLE]2.0.CO;2|bibcode=1953GSAB...64..721K }}</ref>