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Abstract Detail



Paleobotany

Matsunaga, Kelly [1], Herendeen, Patrick [2], Herrera, Fabiany [2], Ichinnorov, Niiden [3], Crane, Peter [4], Shi, Gongle [5].

Ovulate cones of Schizolepidopsis provide insights into the evolution of Pinaceae.

The extinct conifer genus Schizolepidopsis is characterized by deeply bilobed ovuliferous scales bearing two adaxial seeds. Although frequently placed in Pinaceae the evidence for a close relationship with the family is mixed. Resolving the affinities of Schizolepidopsis has important implications for the age of Pinaceae because putative reports of the genus extend into the Late Permian. We describe a new species based on specimens from the Lower Cretaceous of Mongolia and Inner Mongolia, China, which represent the first anatomically preserved occurrences of Schizolepidopsis. Specimens were studied using light microscopy, cellulose-acetate peels, and X-ray micro-computed tomography. To test relationships between Schizolepidopsis and Pinaceae, we performed conifer-wide phylogenetic analyses that included ten previously described fossil conifers, using DNA sequence data and a new morphological matrix of ovulate reproductive characters. Analyses were performed using Bayesian total-evidence and parsimony backbone approaches. The new Schizolepidopsis species possesses key characters of Pinaceae, including those related to pollination biology. Most analyses placed it in crown-group Pinaceae (abietoid clade), with all other Schizolepidopsis species forming a grade along the Pinaceae stem. Uncertainty in the data indicates stem-group affinities of the new species are also possible. This study provides the first conclusive evidence linking Schizolepidopsis with extant Pinaceae. The phylogenetic relationships between extant Pinaceae and Schizolepidopsis suggest that seed wings evolved along the Pinaceae stem and not with the crown group, and that, in combination with developmental genetic evidence, the simple ovuliferous scales of Pinaceae likely evolved from bilobed ovuliferous scales like those of Schizolepidopsis. More broadly, this study provides evidence of a Mesozoic Pinaceae stem group that might extend into the Paleozoic, helping to reconcile the ancient stem divergence of Pinaceae with its relatively recent crown age.


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1 - University Of Kansas, Ecology And Evolutionary Biology, 1200 Sunnysive Ave., Lawrence, KS, 66045, United States
2 - Chicago Botanic Garden, 1000 Lake Cook Road, Glencoe, IL, 60022, USA
3 - Institute of Paleontology and Geology of Mongolian Academy of Sciences, P.O.Box-46/650, Ulaanbaatar, 15160, Mongolia
4 - Oak Spring Garden Foundation, Oak Spring, Upperville, VA, 20184, United States
5 - Nanjing Institute Of Geology And Palaeontology, Chinese Academy Of Sci, 39 East Beijing Road, Nanjing, 32, 210008, China

Keywords:
conifers
phylogenetics
plant evolution
Pinaceae
fossils
Paleobotany.

Presentation Type: Oral Paper
Session: PL6, Paleobotany: Paleozoic/Mesozoic Paleobotany
Location: /
Date: Thursday, July 22nd, 2021
Time: 11:15 AM(EDT)
Number: PL6006
Abstract ID:370
Candidate for Awards:None


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