{{Short description|Extinct genus of angiosperm}} {{Automatic taxobox | fossil_range = Late Cretaceous to Eocene (Campanian-Priabonian), {{fossil range|83.6|33.9}} | image = Platanites marginata (HC106).jpg | image_caption = A specimen of ''Platanites marginata'' from the Hell Creek Formation | taxon = Platanites | authority = Forbes ex Gardner 1851 | subdivision_ranks = Species | subdivision = *{{extinct}}'''''Platanites hebridicus ''''' * {{extinct}}'''''Platanites marginatus ''''' * {{extinct}}'''''Platanites montanus''''' * {{extinct}}'''''Platanites raynoldsii''''' * {{extinct}}'''''Platanites fremontensis''''' {{collapsible list|title=Species pending reassessment| * {{extinct}}'''''Platanites willigeri'''''? }} | synonyms = {{collapsible list|bullets = true |title=<small>Species synonymy</small> |'' Negundo fremontensis'' <br /> }} }}
'''''Platanites''''' is a genus of extinct plane tree (sycamore) that existed during the Late Cretaceous<ref>{{cite web |title=KJ87153 (DMNH 1250) (Cretaceous of the United States) |url=https://paleobiodb.org/classic/basicCollectionSearch?collection_no=48199&is_real_user=1 |website=PBDB.org}}</ref><ref>{{cite web |title=Eagle Formation VB9602 (Cretaceous of the United States) |url=https://paleobiodb.org/classic/basicCollectionSearch?collection_no=27136&is_real_user=1 |website=PBDB.org}}</ref> as well as the Paleocene and Eocene. Fossils are known from North America and Europe.<ref name="Nares-2025">{{Cite journal |last=Nares |first=Francisco R. |last2=Huegele |first2=Indah B. |last3=Manchester |first3=Steven R. |date=2025 |title=Compound-Leaved Platanaceae in the Eocene of Western North America |url=https://www.journals.uchicago.edu/doi/abs/10.1086/732310 |journal=International Journal of Plant Sciences |volume=186 |issue=1 |pages=68–79 |doi=10.1086/732310 |issn=1058-5893|url-access=subscription }}</ref><ref>{{Citation |last=Crane |first=Peter R. |title=Paleobotanical evidence on the early radiation of nonmagnoliid dicotyledons |date=1989 |work=Woody plants — evolution and distribution since the Tertiary |pages=165–191 |url=https://doi.org/10.1007/978-3-7091-3972-1_9 |access-date=2025-08-19 |place=Vienna |publisher=Springer Vienna |isbn=978-3-211-99938-7}}</ref>
==Description== The leaves of ''Platanites'' are said to be compound with three leaflets.<ref name="Nares-2025" /><ref>{{Cite journal |last=PEPPE |first=DANIEL J. |last2=ERICKSON |first2=J. MARK |last3=HICKEY |first3=LEO J. |date=2007 |title=FOSSIL LEAF SPECIES FROM THE FOX HILLS FORMATION (UPPER CRETACEOUS: NORTH DAKOTA, USA) AND THEIR PALEOGEOGRAPHIC SIGNIFICANCE |url=https://doi.org/10.1666/05067.1 |journal=Journal of Paleontology |volume=81 |issue=3 |pages=550–567 |doi=10.1666/05067.1 |issn=0022-3360|url-access=subscription }}</ref> The margins are serrated, with rounded sinuses between the teeth. The petiole is swollen at its base. The terminal leaflet is borne on a short stalk, while the lateral leaflets range from sessile to shortly stalked.<ref name="Nares-2025" /> Some leaf specimens exhibit an unusually elongated tip compared to other material. This difference is not regarded as evidence of a distinct taxon; rather, it is attributed to natural morphological variation within the species, possibly related to leaf position in the tree crown—a pattern also observed in living members of Platanaceae (making it rather common trait among plane trees).<ref name="Nares-2025" /><ref>{{Cite journal |last=Chunxia |first=He |last2=Jiyue |first2=Li |last3=Ming |first3=Guo |last4=Yutao |first4=Wang |last5=Chong |first5=Chen |date=2008-07-01 |title=Changes in leaf photosynthetic characteristics and water use efficiency along with tree height of 4 tree species |url=https://www.sciencedirect.com/science/article/pii/S1872203208600645 |journal=Acta Ecologica Sinica |volume=28 |issue=7 |pages=3008–3016 |doi=10.1016/S1872-2032(08)60064-5 |issn=1872-2032|url-access=subscription }}</ref> ''Platanites'' leaves show no evidence for evergreen adaptations. It was probably deciduous based on petiole morphology.<ref name="Nares-2025" /> Today, the only evergreen plane tree is ''Platanus (Casteneophyllum) kerrii'' with most other plane trees being deciduous.<ref name="Nares-2025" />
==Distribution== Fossils are known from Scotland (such as in the Ardtun Leaf Beds), Montana (such as in the Hell Creek, Ravenscrag and Fort Union Formations), South Dakota (such as in the Hell Creek Formation), North Dakota (such as in the Hell Creek and Fox Hills Formations),<ref name="Johnson-2002">{{Citation |last=Johnson |first=Kirk R. |title=Megaflora of the Hell Creek and lower Fort Union Formations in the western Dakotas: Vegetational response to climate change, the Cretaceous-Tertiary boundary event, and rapid marine transgression |date=2002-09-01 |work=The Hell Creek Formation and the Cretaceous-Tertiary boundary in the northern Great Plains: An Integrated continental record of the end of the Cretaceous |pages=0 |editor-last=Hartman |editor-first=Joseph H. |url=https://doi.org/10.1130/0-8137-2361-2.329 |access-date=2025-08-22 |publisher=Geological Society of America |doi=10.1130/0-8137-2361-2.329 |isbn=978-0-8137-2361-7 |editor2-last=Johnson |editor2-first=Kirk R. |editor3-last=Nichols |editor3-first=Douglas J.|url-access=subscription }}</ref> Utah (such as in the Green River Formation), New Mexico (such as in the Nacimiento and Ojo Alamo Formations), Wyoming (such as in the Eagle and Aycross Formations), Oregon (such as in the Clarno Formation) and Colorado (such as in the Denver and Green River Formations).<ref name="Nares-2025" /> A possible species is known from Poland.<ref name="Nares-2025" />
==Extinction== While common place during the Cretacoues and Paleocene,<ref name="Johnson-2002" /> ''Platanites'' went extinct during the Eocene. Western North America appears to have been the final refuge of ''Platanites'', where the genus persisted only in a few lake settings of the Pacific Northwest and southern Rocky Mountains. No occurrences are currently known from Oligocene or Neogene deposits, implying that the lineage either vanished from the region or became fully extinct near the Eocene–Oligocene boundary. This timing coincides with the global transition from a warmhouse climate to a prolonged coolhouse state.<ref name="Nares-2025" /> ==References== {{Reflist}}
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Category:Platanaceae Category:Mesozoic trees Category:Prehistoric trees Category:Prehistoric angiosperm genera Category:Cretaceous North America Category:Late Cretaceous plants Category:Cenozoic life of Europe Category:Paleocene North America Category:Eocene North America Category:Eocene plants of North America Category:Cretaceous United States Category:Campanian genus first appearances Category:Maastrichtian life Category:Priabonian extinctions Category:Hell Creek Formation Category:Green River Formation Category:Fossil taxa described in 1851 Category:Taxa described in 1851 Category:Eocene life of North America Category:Fossils of Scotland Category:Fossils of Montana Category:Paleontology in North Dakota