Additional fossil specimens of Eophylica (Rhamnaceae) in mid-Cretaceous amber from the Hukawng Valley, Myanmar

  • George O. Poinar, Jr. Oregon State University
  • Kenton L. Chambers Oregon State University

Abstract

The recently described fossil angiosperm genus Eophylica (Rhamnaceae) was based on 18 amber-embedded specimens derived from two sites in northern Myanmar. A vegetatively similar fossil, which came from the same amber mines but which lacked flowers, had been previously described as a putative green alga and given the name Electrophycus. The dimensions and vegetative aspect of that taxon’s holotype specimen are identical with those of the Eophylica fossils. Four additional specimens were acquired by the senior author after the publication of Electrophycus, all of which have a single terminal flower that is either immature or essentially fully formed. Using techniques of floral dissection, high magnification microscopy, and microphotography of the better-developed flowers, we present a more detailed picture of the floral organs, especially the stamens and style, of Eophylica. These flowers differ from the holotype specimen of Eophylica and 3 of its paratypes in that they possess involucral bracts of a so-called ‘pseudanthial head,’ a structure that the authors of Eophylica had only ascribed to certain other paratype specimens of the genus.

References

CHAMBERS, K.L. & G.O. POINAR, JR. 2020. Thymolepis toxandra gen. et sp. nov., a mid-Cretaceous fossil flower with horseshoe-shaped anthers. J. Bot. Res. Inst. Texas 14:57–64.
CREPET, W.L., K.C. NIXON, D. GRIMALDI, & M. RICCIO. 2016. A mosaic Lauralean flower from the Early Cretaceous of Myanmar. Amer. J. Bot. 103:290–297.
CRUICKSHANK, R.D. & K. KO. 2003. Geology of an amber locality in the Hukawng Valley, northern Myanmar. J. Asian Earth Sci. 23:441–455
LIU, Z-J., D. HUANG, C. CAI, & Z. WANG. 2018. The core eudicot boom registered in Myanmar amber. Sci. Rep. 8:16765.
METCALFE, I. 2013. Gondwana dispersion and Asian accretion: tectonic and palaeogeographic evolution of eastern Tethys. J. Asian Earth Sci. 66:1–33.
PILLANS, N.S. 1942. The genus Phylica. J. S. African Bot. 8:1–164.
POINAR, G.O., JR. 2018. Burmese amber: Evidence of Gondwanan origin and Cretaceous dispersion. Historical Biol. 2018:1–6.
POINAR, G.O., JR. & A.E. BROWN. 2019. A green algae (Chaetophorales: Chaetophoraceae) in Burmese amber. Historical Biol. https://doi.org/10.1080/08912963.2019.1616719
POINAR, G.O., JR., R. BUCKLEY, & A. BROWN. 2006. The secrets of Burmese amber. Mid Amer. Paleontol. Soc. Digest 29:20–29.
POINAR, G.O., JR. & K.L. CHAMBERS. 2020. Chainandra zeugostylus gen. et sp. nov., a mid-Cretaceous amber fossil with sagittate anthers opening widely at maturity. J. Bot. Res. Inst. Texas 14:357–372.
POINAR, G.O., JR. & S. ELLENBERGER. 2020. Burmese amber fossils, mining, sales and profits. Geoconserv. Res. 3:12–16.
POINAR, G.O., JR., G.J.B. LAMBERT, & Y. WU. 2007. Araucarian source of fossiliferous Burmese amber: Spectroscopic and anatomical evidence. J. Bot. Res. Texas 1:449–455.
POINAR, G.O., JR., K.L. CHAMBERS, U.T. IWANIEC, & F.E. VEGA. 2020. Valviloculus pleristaminis gen. et sp. nov., a Lauralean fossil flower with valvate anthers from mid-Cretaceous Myanmar amber. J. Bot. Res. Inst. Texas 14:359–366.
SHI, C. ET AL. (27 AUTHORS). 2022. Fire-prone Rhamnaceae with South African affinities in Cretaceous Myanmar amber. Nature Pl. https://doi.org/10.1038/s41477-021-01091-w
SHI, G., D.A. GRIMALDI, G.E. HARLOW, J. WANG, M. YANG, W. LEI, Q. LI, & X. LI. 2012. Age constraint on Burmese amber based on U–Pb dating of zircons. Cretac. Res. 37:155–163.
SOKOL, J. 2019. Troubled treasure. Science 364:722–729.
WESTERWEEL, J. ET AL. 2019. Burma Terrane part of the Trans-Tethyan Arc during collision with India according to palaeomagnetic data. Nat. Geosci. 12:5–6.
XIA, F.Y., G. YANG, Q. ZHANG, & G.L. SHI. 2015. Amber lives through time and space. Beijing Science Press. (In Chinese).
XING, L.D. & L. QIU. 2020. Zircon U–Pb age constraints on the Hkamti amber biota in northern Myanmar. Palaeogeogr. Palaeoclimatol. Palaeoecol. 558:109960.
Published
2022-07-15
How to Cite
Poinar, Jr., G. O., & Chambers, K. L. (2022). Additional fossil specimens of Eophylica (Rhamnaceae) in mid-Cretaceous amber from the Hukawng Valley, Myanmar. Journal of the Botanical Research Institute of Texas, 16(1), 63-72. https://doi.org/10.17348/jbrit.v16.i1.1221