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Eobowenia gen. nov. from the Early Cretaceous of Patagonia: indication for an early divergence of Bowenia ?

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ABSTRACT

Background: Even if they are considered the quintessential “living fossils”, the fossil record of the extant genera of the Cycadales is quite poor, and only extends as far back as the Cenozoic. This lack of data represents a huge hindrance for the reconstruction of the recent history of this important group. Among extant genera, Bowenia (or cuticles resembling those of extant Bowenia) has been recorded in sediments from the Late Cretaceous and the Eocene of Australia, but its phylogenetic placement and the inference from molecular dating still imply a long ghost lineage for this genus.

Results: We re-examine the fossil foliage Almargemia incrassata from the Lower Cretaceous Anfiteatro de Ticó Formation in Patagonia, Argentina, in the light of a comparative cuticular analysis of extant Zamiaceae. We identify important differences with the other member of the genus, viz. A. dentata, and bring to light some interesting characters shared exclusively between A. incrassata and extant Bowenia. We interpret our results to necessitate the erection of the new genus Eobowenia to accommodate the fossil leaf earlier assigned as Almargemia incrassata. We then perfom phylogenetic analyses, including the first combined morphological and molecular analysis of the Cycadales, that indicate that the newly erected genus could be related to extant Bowenia.

Conclusion: Eobowenia incrassata could represent an important clue for the understanding of evolution and biogeography of the extant genus Bowenia, as the presence of Eobowenia in Patagonia is yet another piece of the biogeographic puzzle that links southern South America with Australasia.

Electronic supplementary material: The online version of this article (doi:10.1186/s12862-017-0943-x) contains supplementary material, which is available to authorized users.

No MeSH data available.


Eobowenia incrassata gen. nov., comb. nov., from the Aptian (Lower Cretaceous) of Patagonia, Argentina. a Overview of an apical leaf fragment (specimen v52264). b Interpretative drawing of the specimen, showing potentially dichotomizing veins. c Light microscopy image of the adaxial cuticle, note the short rows of more heavily cutinised epidermal cells (specimen v52265). d CLSM image of the abaxial cuticle, note the darker staining epidermal cells (specimen v52265). Scale bars: a 10 mm, b 1 mm, c 100 μm
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Fig2: Eobowenia incrassata gen. nov., comb. nov., from the Aptian (Lower Cretaceous) of Patagonia, Argentina. a Overview of an apical leaf fragment (specimen v52264). b Interpretative drawing of the specimen, showing potentially dichotomizing veins. c Light microscopy image of the adaxial cuticle, note the short rows of more heavily cutinised epidermal cells (specimen v52265). d CLSM image of the abaxial cuticle, note the darker staining epidermal cells (specimen v52265). Scale bars: a 10 mm, b 1 mm, c 100 μm

Mentions: Description: Eobowenia incrassata (Fig. 2) is represented by two fragmentary specimens [43]. The three (probably terminal) leaflets on specimen v52264 clearly show the serrate margin, the attachment of the leaflets, and the fine striations present between the veins on the leaflets (Fig. 2 a). These characters were already identified as diagnostic for the species by Archangelsky [43]. The preserved portions of the leaflets are 7.4–9.3 mm long and up to 3.5 mm wide.Fig. 2


Eobowenia gen. nov. from the Early Cretaceous of Patagonia: indication for an early divergence of Bowenia ?
Eobowenia incrassata gen. nov., comb. nov., from the Aptian (Lower Cretaceous) of Patagonia, Argentina. a Overview of an apical leaf fragment (specimen v52264). b Interpretative drawing of the specimen, showing potentially dichotomizing veins. c Light microscopy image of the adaxial cuticle, note the short rows of more heavily cutinised epidermal cells (specimen v52265). d CLSM image of the abaxial cuticle, note the darker staining epidermal cells (specimen v52265). Scale bars: a 10 mm, b 1 mm, c 100 μm
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC5383990&req=5

Fig2: Eobowenia incrassata gen. nov., comb. nov., from the Aptian (Lower Cretaceous) of Patagonia, Argentina. a Overview of an apical leaf fragment (specimen v52264). b Interpretative drawing of the specimen, showing potentially dichotomizing veins. c Light microscopy image of the adaxial cuticle, note the short rows of more heavily cutinised epidermal cells (specimen v52265). d CLSM image of the abaxial cuticle, note the darker staining epidermal cells (specimen v52265). Scale bars: a 10 mm, b 1 mm, c 100 μm
Mentions: Description: Eobowenia incrassata (Fig. 2) is represented by two fragmentary specimens [43]. The three (probably terminal) leaflets on specimen v52264 clearly show the serrate margin, the attachment of the leaflets, and the fine striations present between the veins on the leaflets (Fig. 2 a). These characters were already identified as diagnostic for the species by Archangelsky [43]. The preserved portions of the leaflets are 7.4–9.3 mm long and up to 3.5 mm wide.Fig. 2

View Article: PubMed Central - PubMed

ABSTRACT

Background: Even if they are considered the quintessential “living fossils”, the fossil record of the extant genera of the Cycadales is quite poor, and only extends as far back as the Cenozoic. This lack of data represents a huge hindrance for the reconstruction of the recent history of this important group. Among extant genera, Bowenia (or cuticles resembling those of extant Bowenia) has been recorded in sediments from the Late Cretaceous and the Eocene of Australia, but its phylogenetic placement and the inference from molecular dating still imply a long ghost lineage for this genus.

Results: We re-examine the fossil foliage Almargemia incrassata from the Lower Cretaceous Anfiteatro de Ticó Formation in Patagonia, Argentina, in the light of a comparative cuticular analysis of extant Zamiaceae. We identify important differences with the other member of the genus, viz. A. dentata, and bring to light some interesting characters shared exclusively between A. incrassata and extant Bowenia. We interpret our results to necessitate the erection of the new genus Eobowenia to accommodate the fossil leaf earlier assigned as Almargemia incrassata. We then perfom phylogenetic analyses, including the first combined morphological and molecular analysis of the Cycadales, that indicate that the newly erected genus could be related to extant Bowenia.

Conclusion: Eobowenia incrassata could represent an important clue for the understanding of evolution and biogeography of the extant genus Bowenia, as the presence of Eobowenia in Patagonia is yet another piece of the biogeographic puzzle that links southern South America with Australasia.

Electronic supplementary material: The online version of this article (doi:10.1186/s12862-017-0943-x) contains supplementary material, which is available to authorized users.

No MeSH data available.