Quereuxia

Quereuxia Temporal range: Campanian–Paleocene 83–56  Ma PreꞒ Ꞓ O S D C P T J K Pg N
Quereuxia angulata
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Angiosperms
Genus:	† Quereuxia

Quereuxia is an extinct genus of aquatic angiosperms known from fossil leaves and leaf rosettes primarily dating to the Late Cretaceous period. ^[1] It also survived into the Paleocene. ^[2] These plants are notable for their floating growth habit, with morphological features suggesting adaptation to still freshwater environments. ^[3]

Classification

Morphological studies have confirmed the genus' distinctiveness based on features such as heterophyllous leaf arrangements (both simple and compound), floating rosettes, and submerged rhizomatous growth. Quereuxia angulata, the most well-known species, has often been compared to extant members of Trapa (water chestnut), though differences in growth habit and floral morphology have prevented confident placement within any modern family, leaving its exact taxonomic position unresolved. ^[3]

Distribution

Fossils are known from Russia, ^[4] The United States, ^[5] Canada ^[6] and Mongolia. ^[7]

References

1. Hickey, Leo J. (2001). "On the nomenclatural status of the morphogenera, Quereuxia and Trapago". Taxon. 50 (4): 1119–1124. doi:10.2307/1224729. ISSN   1996-8175.
2. Wing, Scott (February 1994). "Flora of the Ravenscrag formation (paleocene), southwestern Saskatchewan, Canada". Review of Palaeobotany and Palynology. 80 (3–4): 341. doi:10.1016/0034-6667(94)90012-4. ISSN   0034-6667.
3. Stockey, Ruth A.; Rothwell, Gar W. (January 1997). "The Aquatic Angiosperm Trapago angulata from the Upper Cretaceous (Maastrichtian) St. Mary River Formation of Southern Alberta". International Journal of Plant Sciences. 158 (1): 83–94. doi:10.1086/297417. ISSN   1058-5893.
4. "Obeshchayushchiy (PIN collection 3901) (Cretaceous of Russian Federation)". PBDB.org.
5. Johnson, Kirk R. (2002-09-01), Hartman, Joseph H.; Johnson, Kirk R.; Nichols, Douglas J. (eds.), "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", The Hell Creek Formation and the Cretaceous-Tertiary boundary in the northern Great Plains: An Integrated continental record of the end of the Cretaceous, Geological Society of America, p. 0, doi:10.1130/0-8137-2361-2.329, ISBN   978-0-8137-2361-7 , retrieved 2025-08-26
6. Aulenback, Kevin R.; LePage, Ben A. (March 1998). "Taxodium wallissii Sp. Nov.: First Occurrence of Taxodium from the Upper Cretaceous". International Journal of Plant Sciences. 159 (2): 367–390. doi:10.1086/297558. ISSN   1058-5893.
7. Khand, Yo.; Badamgarav, D.; Ariunchimeg, Ya.; Barsbold, R. (2000-01-01), Okada, Hakuyu; Mateer, Nlall J. (eds.), "Cretaceous system in Mongolia and its depositional environments", Developments in Palaeontology and Stratigraphy, Cretaceous Environments of Asia, vol. 17, Elsevier, pp. 49–79, retrieved 2025-08-26