A new macrofossil ephedroid plant with unusual bract morphology from the Lower Cretaceous Jiufotang Formation of northeastern China

Abstract

Background: The evolution of the Jehol Biota of western Liaoning in China includes three phases, initiation in the Dabeigou phase, radiation in the Yixian phase, and decline in the Jiufotang phase. Numerous ephedroid macrofossils were reported from the Lower Cretaceous Yixian Formation. However, so far none has been found in the younger Jiufotang Formation (ca. 120.3 Ma) of western Liaoning. Results: Here we report a new species Jianchangia verticillata gen. et sp. nov. with unusual morphology from the Lower Cretaceous of the Jiufotang Formation, Lamadong Village, Jianchang County, Liaoning. This species is the first record of gnetophytes from the Jiufotang Formation. It is similar to other ephedroid species from the Yixian Formation in possessing linear leaves with parallel veins, jointed shoots with swollen nodes and longitudinally furrowed internodes, and ovulate cones possessing two whorls of bracts enclosing two chlamydosperms, but differs from all known species by the ovulate cone having multiple fine linear verticillate bracts. Conclusions: This study expands our knowledge about the diversity of early gnetophytes in the Lower Cretaceous, and demonstrates the lineage continuity of gnetophytes from the Yixian Formation to the younger Jiufotang Formation.

Node ages, relationships, and phylogenomic incongruence in an ancient gymnosperm lineage – Phylogeny of Ephedra revisited

“…Fossils from the Early Cretaceous document that many vegetative and reproductive morphological features of modern‐day Ephedra were already present around 125 million years ago (e.g., Rydin & al., 2004, 2006a; Bolinder & al., 2016b; Han & al., 2016). The Early Cretaceous held a substantial global diversity of plants with an indeterminate but clear affinity to ephedroids/gnetaleans, at least at low paleolatitudes (e.g., Krassilov, 1982, 1986; Krassilov & al., 1998; Y. Yang & al., 2005, 2013, 2018, 2020; Rydin & al., 2006b, 2010; Friis & al., 2007, 2019; X. Wang & Zheng, 2010; Ricardi‐Branco & al., 2013). Most of the Ephedra ‐like fossils are difficult to place phylogenetically, partly because of their relatively poor preservation state but also because there are few diagnostic characters that clearly distinguish Ephedra from the remaining Gnetales.…”

“…The Gnetales (comprising the three extant genera Ephedra , Gnetum L. and Welwitschia Hook.f.) have a long, diverse and intriguing evolutionary history that extends at least to the Early Cretaceous (among many, Krassilov, 1982, 1986; Krassilov & Bugdaeva, 1982; Crane & Upchurch, 1987; Osborn & al., 1993; Crane, 1996; Mohr & Friis, 2000; Rydin & al., 2003, 2004, 2006b, 2010; Y. Yang & al., 2005, 2013, 2018, 2020; Friis & al., 2007, 2013, 2014, 2019; Rydin & Friis, 2010; X. Wang & Zheng, 2010; Ickert‐Bond & Rydin, 2011; Norbäck Ivarsson, 2013; Rothwell & Stockey, 2013; Bolinder & al., 2015, 2016a,b; Hou & al., 2015; Rydin & Bolinder, 2015; Han & al., 2016; Rydin & Hoorn, 2016). Extant diversity is limited to some 100 species, most of them in Ephedra (Ickert‐Bond & Renner, 2016).…”

A New Gnetalean Macrofossil from the Mid-Jurassic Daohugou Formation

“…The three living families of gnetophytes usually possess decussate phyllotaxy [1,4], but sometimes ternately whorled phyllotaxy does occur in Ephedra [8,62,63]. Most gnetalean macrofossils do have decussate phyllotaxy, i.e., opposite leaves or branching pattern (Table 1) [18][19][20][21][22][23][24]28,29,38,50]; Alloephedra xingxuei J.R. Tao et Y. Yang is considered as having alternate leaves, which is arguable due to the poor preservation of vegetative characters [17,25]. Our new macrofossil reported here shows that the gnetophytes possess decussate phyllotaxy, so it is reasonable to infer that the decussate or ternately whorled phyllotaxy is conservative and a synapomorphic character of the gnetophytes.…”

“…Paleobotanical studies can provide convincing evidence of the evolutionary history of organisms. Numerous gnetalean macro-and mesofossils have been reported from the Mid-Jurassic to Early Cretaceous, i.e., Asia [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31], Australia [32], Europe [33][34][35][36][37], North America [33][34][35][36][38][39][40] and South America [41][42][43][44][45][46][47][48][49][50]. These fossils show a wide distribution range (Australia, NE China, Mongolia, United States of America, Brazil and Portugal) and huge morphological diversity [22,23,25,27,33,35,…”

“…These fossils show a wide distribution range (Australia, NE China, Mongolia, United States of America, Brazil and Portugal) and huge morphological diversity [22,23,25,27,33,35,42,50]. In the Early Cretaceous, Ephedraceae occurred in Oceania (Australia), Asia (Northeast China and Mongolia), southern Europe (Portugal) and South America (Brazil) [22][23][24]28,29,32,33]; Welwitschiaceae Plants 2023, 12, 1749 2 of 16 lived in southern Europe, North America and South America [35,41,42]; and Gnetaceae was apparently restricted to Asia (Northeast China) [27]. Thus far, more than 54 species have been recorded from the Mesozoic.…”