Abstract
Abundant plant fossils were found in the Upper Miocene Shengxian Formation, eastern Zhejiang Province, China, among which Trapa belongs to a dominant population. The fossil fruits of Trapa were well preserved with abundant details. However, due to compaction during fossilization, Trapa fruits were often flattened, leading to the loss of some characteristic features. Thereby, a bias in taxonomic and phylogenetic studies would occur when such studies were based on these fruit fossils. In this study, we present the first quantitative three-dimensional reconstruction of compressed Trapa fruit fossils to restore their original morphology prior to burial. This approach provides a novel perspective for the identification and classification of compressed fruit fossils. The three-dimensional reconstruction of Trapa fruit fossils enabled accurate comparisons with extant species. We subsequently identified it as a new species, named Trapa radiatiformis L. Xiao sp. nov., revealing differences from previously known taxa of Trapa . Importantly, our comparison suggests that the long lower horns and residual stalk may represent inherent characteristics of early Trapa fruits. However, these traits gradually degenerated during fruit evolution, resulting in morphological simplification during geological time. T. radiatiformis with primitive features exhibits good resemblance to Trapa natans fruit characteristics, which means it may be an ancestor of T. natans. We summarize the palaeogeographic distribution of fossil Trapa using previously published literature and demonstrate that the genus was most prosperous in the Miocene and exhibited the same distribution as that at present. Additionally, through detailed morphological comparisons between Trapa and Hemitrapa fruits, along with phylogenetic analysis within the Primotrapa genus itself, we propose a homology between Trapa and Hemitrapa , suggesting that they could have a common ancestor. • The present fossil is assigned to Trapa radiatiformis L. Xiao sp. nov. based on its morphological characteristics designates it as the ancestral species of Trapa natans. • The quantified Three-Dimensional recovery of Trapa radiatiformis L. Xiao sp. nov., which reduces identification errors and provides a new method for the study of compressed fruit fossils. • Comparing the morphological characteristics of the discovered fossils of the genus Trapa with those of the genus Hemitrapa and Primotrapa , the “Homology theory” relationship between the Trapa and the Hemitrapa may be more convincing.
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Claims 8
Claim · model-written summary
Three-dimensional reconstruction enabled accurate comparison of compressed Trapa fruit fossils with extant species.
TrapaOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The three-dimensional reconstruction of Trapa fruit fossils enabled accurate comparisons with extant species.”
Claim · model-written summary
The fossil was identified as a new species, Trapa radiatiformis L. Xiao sp. nov.
Verbatim
e0“We subsequently identified it as a new species, named Trapa radiatiformis L. Xiao sp. nov., revealing differences from previously known taxa of Trapa .”
Claim · model-written summary
Early Trapa fruits may inherently have long lower horns and a residual stalk.
- Organ / stage
- fruitse0
- Outcome
- long lower horns and residual stalke0
- Qualifier
- may represent inherent characteristics of early Trapa fruitse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“our comparison suggests that the long lower horns and residual stalk may represent inherent characteristics of early Trapa fruits.”
Claim · model-written summary
The lower horns and residual stalk gradually degenerated during fruit evolution.
- Organ / stage
- fruite0
- Outcome
- long lower horns and residual stalke1
- Direction
- gradually degeneratede0
- Qualifier
- during geological timee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“these traits gradually degenerated during fruit evolution, resulting in morphological simplification during geological time.”
e1“long lower horns and residual stalk”
e2“early Trapa fruits”
Claim · model-written summary
Trapa radiatiformis resembles Trapa natans fruit morphology and may be its ancestor.
Verbatim
e0“T. radiatiformis with primitive features exhibits good resemblance to Trapa natans fruit characteristics, which means it may be an ancestor of T. natans.”
Claim · model-written summary
Fossil Trapa was most prosperous in the Miocene.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the genus was most prosperous in the Miocene”
e1“fossil Trapa”
Claim · model-written summary
Fossil Trapa had the same distribution as at present.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“exhibited the same distribution as that at present”
e1“fossil Trapa”
Claim · model-written summary
Trapa and Hemitrapa may be homologous and share a common ancestor.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“we propose a homology between Trapa and Hemitrapa , suggesting that they could have a common ancestor.”