Early Cretaceous abietoid Pinaceae from Mongolia and the history of seed scale shedding
Early Cretaceous abietoid Pinaceae from Mongolia and the history of seed scale shedding
复制标题
蒙古早白垩世松科松科植物及其籽鳞脱落历史
DOI：
10.1002/ajb2.1713
复制
发表时间：
2021
影响因子：
3
通讯作者：
Herendeen, Patrick S.
中科院分区：
文献类型：
--
作者：
Herrera, Fabiany;Shi, Gongle;Bickner, Maya A.;Ichinnorov, Niiden;Leslie, Andrew B.;Crane, Peter R.;Herendeen, Patrick S.
现存松科的球果表现出两种种子释放机制。在“弯曲器”中，锥鳞保持附着在中心轴上，同时弯曲并彼此分离以释放种子。在“脱落器”中，鳞片从轴上脱落，种子要么保持附着在鳞片上，要么脱落。从侏罗纪到早白垩世，松科的早期化石历史主要是由弯曲的种子锥，而脱落的化石锥提供的系统信息一直被忽视，很少与基于压缩和矿化标本的数据相结合。我们描述了最早的和最好的记录证据的“shedder”种子锥从Aptian-Albian的Mongolia.MethodsLignite样品Tevshiin Govi地方分解在水中，洗涤，并在空气中干燥。化石进行了比较，以现存的松科材料使用LM和CT scans. ResultsLepidocalmellonaegen。et sp. nov.的特征是成熟时脱落的种球和倒卵形的苞片鳞片复合体，该复合体具有独特的肋状表面和被丰富的毛状体覆盖的背面。珠鳞有约。30-40个树脂道，但只有少数木质部靠近轴的附件。种子珠被中有树脂囊泡。系统发育分析表明，Lepidocasusas是雪松的姊妹种，属于冷杉属。Mellonaeraises的问题，其潜在的生态功能在化石和生活的松科的球果。Lepidocalypellonaealso表明，脱落扩散综合征，一个功能，往往被忽视，在松科的历史早期演化在早白垩世。
PremiseSeed cones of extant Pinaceae exhibit two mechanisms of seed release. In “flexers” the cone scales remain attached to the central axis, while flexing and separating from each other to release the seeds. In “shedders” scales are shed from the axis, with the seeds either remaining attached to the scale or becoming detached. The early fossil history of Pinaceae from the Jurassic to Early Cretaceous is dominated by flexing seed cones, while the systematic information provided by shedding fossil cones has been overlooked and rarely integrated with data based on compression and permineralized specimens. We describe the earliest and best‐documented evidence of a “shedder” seed cone from the Aptian–Albian of Mongolia.MethodsLignite samples from Tevshiin Govi locality were disaggregated in water, washed, and dried in air. Fossils were compared to material of extant Pinaceae using LM and CT scans.ResultsLepidocasus mellonaegen. et sp. nov. is characterized by a seed cone that disarticulated at maturity and shed obovate bract–scale complexes that have a distinctive ribbed surface and an abaxial surface covered with abundant trichomes. The ovuliferous scale has ca. 30–40 resin canals, but only scarce xylem near the attachment to the cone axis. Resin vesicles are present in the seed integument. Phylogenetic analysis placesLepidocasusas sister to extantCedruswithin the abietoid grade.ConclusionsThe exquisite preservation of the trichomes inL. mellonaeraises questions about their potential ecological function in the cones of fossil and living Pinaceae.Lepidocasus mellonaealso shows that a shedding dispersal syndrome, a feature that has often been overlooked, evolved early in the history of Pinaceae during the Early Cretaceous.