A recently published review by Herendeen et al. is misleading, self-centered, self-praising, and self-conflicting. They excluded the famous early angiosperm Archaefructus from their list of exemplar angiosperms, which contained only fossil plants they published themselves, leaving the impression that they were only authoritative on the origin and early history of angiosperms. Their 57-year-old “No Angiosperms Until the Cretaceous” conception does not reflect the truth about the origin and early history of angiosperms. Reinforcing such vapidly repeated statement does not help resolving any problem in science but leads to no solution for the origin of angiosperms. The authors tried to establish a criterion identifying a fossil angiosperm but their own exemplar angiosperm Monetianthus overturns their own criterion. Apparently, such a review does not positively contribute much to science.
The age of the angiosperms is a question of importance in botany because the answer to this question is hinged to the solution of many problems in various branches of botany. Palaeobotanists are the major group of scientists trying to answer this question. Unlike other botanists working on extant plants, palaeobotanists build their hypotheses mainly based on fossil evidence, not on reasoning, inferring, or imaginations.
On March 3, 2017, Nature Plants published a review titled as “Palaeobotanical redux: revisiting the age of the angiosperms” authored by Herendeen et al. [ 1 ]. The review repeated a conclusion that was drawn 57 years before, namely, “No angiosperms until the Cretaceous”. This statement on the history of angiosperms apparently does not reflect the progress made in palaeobotany and molecular systematics, both of which suggest pre-Cretaceous origin and history of angiosperms [ 2 - 22 ]. Herendeen et al. did not achieve a balanced view of the current fossil record of angiosperms, considering the following flaws inflicting the review.
In the review, they took effort to prove that Euanthus is closely comparable to Tsuga, without showing supporting evidence of key features. In the caption of their
Herendeen et al. claimed that they found “resin bodies” and “pollen sacs” in Solaranthus but none of their figures supported such claims. Uncritically, they accepted the conclusion of Deng et al. [ 23 ], who showed neither pollen sacs nor origin of pollen grains. Deng et al. [ 23 ] thought that Wang and Zheng [ 16 ] had misinterpreted the “pollen sacs” (in Deng et al.’s sense) as “tepals”. The funny thing is that the specimens Deng et al. studied had no “tepals”, namely, no “pollen sacs” (in Deng et al.’s sense). Then two questions have to be answered before believing Deng et al.: 1) Did Deng et al. really study the plant called Solaranthus? 2) Without so-called “pollen sacs” (in Deng et al.’s sense), where came their in situ pollen grains? Herendeen et al. ignored the well-documented stamens with in situ monocolpate pollen grains in Solaranthus [ 22 ]. Their “resin body” interpretation apparently cannot account for the assumed ovule on the ovary bottom of Solaranthus shown in Figures 2(a)-(d). So the doubt over Solaranthus as an angiosperm both by Deng et al. and Herendeen et al. is groundless, making their conclusion tentative.
Their list of “exemplar” early angiosperms is 100% of their own and even named after one of themselves! The motive of such listing is never released to the public, but it is obviously self-centered. Their first “exemplar” early angiosperm, Monetianthus, was initially asserted as the “oldest” fossil angiosperm, with a Nymphaealean affinity [ 24 ] (an affinity soon rejected [ 25 ]), but was later found much younger than initially claimed [ 26 - 28 ] and thus has little to do with “EARLY” angiosperms. The pre-existing much older famous Archaefructus [ 18 ] was fully and consistently ignored in both publications of Monetianthus [ 24 , 28 ]. Friis et al. gave up the championship later [ 28 ], for unstated reason. Despite ONE integument shown clearly in
The most formidable trend in current palaeobotany is that an increasing number of authors in palaeobotany (including some of Herendeen et al.) are misinterpreting data according to their own academic needs. Besides the above assertion of two integuments in Monetianthus [ 28 ], similar assertions of ONE (instead of MORE) seed in so-called “Umkomasia” [ 30 ], TWO (instead of ONE) veins in Pseudotorellia [ 31 , 32 ], and “FREE” (instead of FUSED) carpels in Kajanthus [ 33 ] by similar authors have formed a line of poor publications in palaeobotany. Such errors are obvious, especially when
Although angio-ovuly is the only consistent difference that separates angiosperms from gymnosperms [ 11 , 18 , 36 ], Herendeen et al. [ 1 ] added three more features to the criterion and, incredibly, they failed to obey their OWN rule themselves because the first “exemplar” early angiosperm Monetianthus does satisfy their own criterion! Herendeen et al. [ 1 ] rejected Juraherba bodae as an angiosperm based on an excuse: “the leaf is too thin” (a feature not among the criterion they proposed). Such a whimsical treatments is unprecedented in botany!
Without showing any evidence, they spent just 1 sentence to nullify Yuhania documented by a paper of 11 pages, 0.5 sentence on Xingxueanthus of 9 pages, and 1.5 sentences on Schmeissneria of 23 pages. These pre-Cretaceous angiosperms were recognized on the basis of presence of enclosed ovules, a feature proposed and applied by various authors [ 11 , 18 , 36 ]. Such a parsimony in wording has little to with authority of Herendeen et al. but reflects their diffidence in their treatments.
Herendeen et al. gave misleading impressions as if some of early angiosperms had been rejected by a third party despite the fact is not so. The paper Herendeen et al. cited to nullify the angiosperm affinity of Schmeissneria [ 37 ] actually had little to do with true Schmeissneria, as fully refuted before (Page 716-717) [ 3 ]. The way Herendeen et al. treated Liaoningfructus implied that Wong et al. [ 38 ] had transferred Liaoningfructus into Archaeamphora/Liaoningocladus. But the fact is that Wong et al. [ 38 ] have never even mentioned Liaoningfructus at all throughout their publication. In all these cases, although Herendeen et al. did not release their own true motive, the consequence is obvious: the readers were misled.
The above mistreatments of information heavily undermine the “No-Angiosperms-Until-Cretaceous” conclusion, which was re-claimed by Herendeen et al. [ 1 ]. It is risky and takes a great courage for a scientist to endorse and repeat an old conclusion that was based on data available decades before. Doing so is detrimental to palaeobotany, which is a vivid, not fossilized, science.
This research was supported by the National Natural Science Foundation of China (41688103, 91514302, 91114201, 41572046), Strategic Priority Research Program (B) of Chinese Academy of Sciences (Grant No. XDPB05, XDB18000000). This is a contribution to UNESCO IGCP632.