Chicago Botanic Garden, Glencoe, Illinois, 60022, USA.
State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology and Center for Excellence in Life and Paleoenvironment, Chinese Academy of Sciences, Nanjing, 210008, China.
Am J Bot. 2021 Aug;108(8):1483-1499. doi: 10.1002/ajb2.1713. Epub 2021 Aug 29.
Seed 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.
Lignite 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.
Lepidocasus mellonae gen. 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 places Lepidocasus as sister to extant Cedrus within the abietoid grade.
The exquisite preservation of the trichomes in L. mellonae raises questions about their potential ecological function in the cones of fossil and living Pinaceae. Lepidocasus mellonae also shows that a shedding dispersal syndrome, a feature that has often been overlooked, evolved early in the history of Pinaceae during the Early Cretaceous.
现存的松科植物的种子球果表现出两种种子释放机制。在“弯曲型”中，鳞片仍然附着在中央轴上，同时弯曲并彼此分离以释放种子。在“脱落型”中，鳞片从轴上脱落，种子要么附着在鳞片上，要么脱落。从侏罗纪到早白垩世，松科植物的早期化石历史主要由弯曲的种子球果主导，而脱落的化石球果提供的系统信息被忽视了，很少与基于压缩和矿化标本的数据相结合。我们描述了来自蒙古早白垩世的最早和记录最完善的“脱落型”种子球果的证据。
特维希因戈维（Tevshiin Govi）地区的褐煤样本在水中分散，水洗，然后在空气中干燥。使用 LM 和 CT 扫描将化石与现存松科植物的材料进行比较。
Lepidocasus mellonae gen. et sp. nov. 的特征是成熟时会分离的种子球果和脱落的倒卵形苞片鳞片复合体，具有独特的脊状表面和背面覆盖着大量毛状体。胚珠鳞片有大约 30-40 个树脂管，但在与轴连接的附近只有很少的木质部。树脂囊存在于种子的外皮中。系统发育分析将 Lepidocasus 置于雪松属内的柏科类群中。
Lepidocasus mellonae 中毛状体的精美保存提出了关于它们在化石和现存松科植物的球果中潜在生态功能的问题。Lepidocasus mellonae 还表明，脱落传播综合征，这一特征在松科植物的早期历史中经常被忽视，在早白垩世早期就已经进化。
