Dinosaur bonebed amber from an original swamp forest soil
Figures
![](https://iiif.elifesciences.org/lax/72477%2Felife-72477-fig1-v1.tif/full/617,/0/default.jpg)
The Lower Cretaceous vertebrate bonebed and amber site of Ariño.
(A) Geographical and geological location; modified from Alcalá et al., 2012 (B) Stratigraphic location of the level AR-1; general stratigraphic log from the Oliete Sub-basin, modified from Kirkland et al., 2013, is shown at the left, together with the location of the level AR-1 (red star); a section of the latter, including the stratigraphic location of the amber deposit studied herein, is shown at the right. (C) Santa María open-pit coal mine with indication of the level AR-1 and the two excavated areas rich in aerial amber (yellow dots); the bottom of the open-pit coal is at the right. (D) One of the 160+ bone concentrations found in Ariño, AR-1/10, during vertebrate fieldwork in 2010, showing the holotype of the nodosaurid Europelta carbonensis; metal dustpan ~30 cm long. (E) Root marks at the top of the carbonates below the level AR-1; scale bar, 1 cm. (F) Carbonates right below the level AR-1, displaying edaphic features at the top. (G) Detail photograph of the level AR-1 showing the lower root layer (with amber from resin exuded by roots) and the upper litter layer (with amber from resin exuded by trunk and branches); centimetric scale. See also Video 1.
![](https://iiif.elifesciences.org/lax/72477%2Felife-72477-fig2-v1.tif/full/617,/0/default.jpg)
Diversity of amber pieces from the AR-1 level and Pleistocene copal pieces for comparison.
(A) Kidney-shaped amber piece (root layer). (B) Aerial amber piece (litter layer), corresponding to a resin flow, after partially removing surrounding rock during fieldwork. (C) Kidney-shaped amber piece (AR-1-A-2019.93) from the root layer. (D, E) Two different areas of the external surface from a fragment detached from the piece in (C), showing the preserved delicate surface microprotrusions and no evidence of linear grooves. (F) Kidney-shaped amber piece (root layer) showing the internal banding pattern (AR-1-A-2019.132). (G) Triphasic (solid+ liquid + gas) bubble-like inclusions in a kidney-shaped amber piece (AR-1-A-2019.130). (H) Two pyrite cuboctahedrons in an alleged empty space left by a fluid inclusion (amber piece AR-1-A-2019.86). (I) Needle-shaped crystals from an iron sulphate (likely szomolnokite) growing inward from the walls in an alleged empty space left by a fluid inclusion (amber piece AR-1-A-2019.129). (J) Kidney-shaped piece of Pleistocene copal associated to an Agathis australis root from an overturned stump in Waipapakauri (North Island, New Zealand). (K) Pleistocene copal pieces associated to the root system of the same A. australis stump; coin 2.65 cm in diameter. Scale bars, 2 cm (A–C, F, J), 0.5 mm (D), 1 mm (E), 0.03 mm (G), 0.2 mm (H), and 0.1 mm (I). See also Video 1.
![](https://iiif.elifesciences.org/lax/72477%2Felife-72477-fig2-figsupp1-v1.tif/full/617,/0/default.jpg)
Strictly in situ (autochthonous) kidney-shaped amber pieces from the root layer of the lower Albian bonebed level AR-1 of Ariño.
(A) Slightly elongate piece exposed by the weathering, but not moved, lacking a detached small surface fragment (left). (B, C) Two rounded and slightly elongate pieces (white arrows in (B) and black arrow in (C)) partially exposed during excavation (piece diameter in (B) = 9 cm; pickaxe length in (C) = 35 cm). (D) Strictly in situ piece fragmented by the weathering, and fragments of another piece on the right (paper strip = 4 cm). (E) Piece partially exposed in the sidewall of a small gully excavated by rain (piece diameter = ca. 7.5 cm). (F) Irregular in situ piece indicated with an arrow; centimetric scale. (G) Crumbled amber piece (pickaxe length = 35 cm). (D, E) excavated during July 2018 and the rest during May 2019.
![](https://iiif.elifesciences.org/lax/72477%2Felife-72477-fig2-figsupp2-v1.tif/full/617,/0/default.jpg)
Litter layer of the lower Albian bonebed level AR-1 of Ariño.
(A) Plant remains, most likely elongate charcoalified wood pieces (coin diameter = 2.3 cm). (B, C) Strictly ex situ (autochthonous) aerial amber pieces (arrows) and elongate woody remains ((B) is the enlarged inset in (C)). (D) Strictly ex situ flattened amber piece most likely originated from resin coating the trunk or infilling a broken trunk. (E) Strictly ex situ stalactite-shaped aerial amber piece. (F) Assortment of aerial amber piece fragments. (A, D–F) excavated during July 2019 and the rest during May 2019. Scale bars, 2 cm (C), and 1 cm (D, E).
![](https://iiif.elifesciences.org/lax/72477%2Felife-72477-fig2-figsupp3-v1.tif/full/617,/0/default.jpg)
Amber pieces with taphonomic interest from the level AR-1 of Ariño.
(A) EDS analysis of the needle-shaped crystals from an iron sulphate (likely szomolnokite) growing inward from the walls in the alleged empty space left by a fluid bubble-like inclusion of an amber piece (AR-1-A-2019.129). (B–D) Small, almost spherical amber masses from the litter layer (AR-1-A-2019.131, AR-1-A-2019.134 and AR-1-A-2019.133, respectively). (E) Surface of a peculiar amber piece found in the litter layer, showing surface borings and linear grooves (AR-1-A-2019.79). Scale bars, 0.1 mm (A), 5 mm (B), 1 cm (C, D), and 1 mm (E).
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Physicochemical characterisation of the Lower Cretaceous amber from Ariño.
(A) Infrared (FTIR) spectra obtained from two aerial amber pieces (litter layer); a spectrum from San Just amber (upper Albian) is provided for comparison; arrows indicate the main differences between Ariño and San Just ambers, at around 1200 and 500 cm–1; resolution = 4 cm–1. (B) Gas chromatography-mass spectrometry (GC-MS) trace for the underivatised total solvent extract of aerial amber, showing the structures of the main identified terpenoids, referred herein using Roman numerals (full formulation provided in Figure 3—figure supplement 1B); TMN = trimethylnaphthalenes; the analysed aerial amber is shown at the top right (scale bar 0.5 mm).
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Figure 3—source data 1
FTIR data of the Ariño amber 1.
- https://cdn.elifesciences.org/articles/72477/elife-72477-fig3-data1-v1.csv
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Figure 3—source data 2
FTIR data of the Ariño amber 2.
- https://cdn.elifesciences.org/articles/72477/elife-72477-fig3-data2-v1.csv
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Figure 3—source data 3
FTIR data of the San Just amber.
- https://cdn.elifesciences.org/articles/72477/elife-72477-fig3-data3-v1.csv
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Figure 3—source data 4
GC-MS data of the Ariño amber.
- https://cdn.elifesciences.org/articles/72477/elife-72477-fig3-data4-v1.zip
![](https://iiif.elifesciences.org/lax/72477%2Felife-72477-fig3-figsupp1-v1.tif/full/617,/0/default.jpg)
Physicochemical characterisation of the Lower Cretaceous amber from Ariño.
(A) Gas chromatography-mass spectrometry (GC-MS) chromatogram corresponding to the polar fraction of the organic extract of the Ariño amber, showing labdanoic acids as main components; decarboxylation and disproportionation of labdanoic acids lead to the main hydrocarbons found, diterpenes of the labdane family. (B) Chemical structures cited in the work.
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Faunal bioinclusions from the Lower Cretaceous bonebed amber of Ariño.
(A) A rhagidiid mite, the oldest known (Acari: Rhagidiidae; AR-1-A-2019.71). (B) An immature thrips (Thysanoptera; AR-1-A-2019.114.2). (C) An adult thrips (Thysanoptera; AR-1-A-2019.40). (D) A whitefly (Hemiptera: Aleyrodidae; AR-1-A-2019.100.1). (E) A ditrysian lepidopteran larva (AR-1-A-2019.95.1). (F) A Burmazelmira sp. fly (Diptera: †Archizelmiridae: AR-1-A-2019.95.2). (G) A false fairy wasp, the oldest known (Hymenoptera: Mymarommatoidea; AR-1-A-2019.61). (H) A superbly preserved platygastroid wasp (Hymenoptera: Platygastroidea; AR-1-A-2019.95.3). (I) A serphitid wasp, the oldest known (Hymenoptera: †Serphitidae; AR-1-A-2019.94.8). (J) A feather barb fragment with pennaceous structure (Theropoda; AR-1-A-2019.53). Scale bars, 0.2 mm (A–C, G), 0.5 mm (D, F, H, I), 1 mm (E), and 0.1 mm (J).
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Diverse bioinclusions in amber from the level AR-1 of Ariño.
(A) Plant remain (AR-1-A-2019.114.3). (B–E) Amber-infilled plant tissue preserving the cellular structure that could correspond to suber (cork) (AR-1-A-2018.1): (B) Preparation (transversal view); (C–E) SEM images: (C) in longitudinal and oblique view, (D) in transversal and oblique view, and (E) in transversal view. (F) A tangled spiderweb portion (AR-1-A-2019.95.5). (G) Detail photograph of a spiderweb strand found in the former, with glue droplets marked with arrowheads. (H) Spider showing the inner body structure in the surface of a broken amber piece (AR-1-A-2019.76). (I) Thrips showing a thin milky coat (AR-1-A-2019.114.1). Scale bars, 0.2 mm (A, C), 0.5 mm (B, F, H, I), 0.3 mm (D), 0.02 mm (E), and 0.05 mm (G).
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Insect bioinclusions in amber from the level AR-1 of Ariño.
(A) An aphidoid (Hemiptera; AR-1-A-2019.103). (B) Wing impression on amber surface probabñy belonging to Berothidae (Neuroptera; AR-1-A-2019.83). (C) A tentative †Paradoxosisyrinae specimen (Neuroptera: Sisyridae; AR-1-A-2019.128.1). (D) A probable Ptinidae specimen (Coleoptera; AR-1-A-2019.44). (E) A probable Cantharidae specimen (Coleoptera; AR-1-A-2019.118.1). Scale bars, 0.5 mm (A, C, D), and 1 mm (B, E).
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Charophyte (A–L), palynomorph (M–T), and ostracod (U–EE) records sampled from level AR-1 of Ariño.
(A–D) Atopochara trivolvis var. trivolvis (†Clavatoraceae): (A, B) Lateral views (AR-1-CH-004 and AR-1-CH-005, respectively); (C) Basal view (AR-1-CH-007); (D) Apical view (AR-1-CH-008); cell lettering after Grambast, 1968. (E–J) Clavator harrisii var. harrisii (†Clavatoraceae): (E) Lateral view (AR-1-CH-009); (F) Adaxial view (AR-1-CH-011); (G) Abaxial view morphotype II (AR-1-CH-013); (H) Abaxial view morphotype III (AR-1-CH-014); (I) Abaxial view morphotype IV (AR-1-CH-015); (J) Basal view (AR-1-CH-017) with indication of adaxial (ad) and abaxial (ab) sides. (K) Clavatoraxis sp. (†Clavatoraceae) (AR-1-CH-019); the arrowhead indicates the zig-zag line at the central part of the internode. (L) aff. Mesochara harrisii (Characeae) in lateral view (AR-1-CH-001). (M) Chomotriletes minor (ARN-03). (N) Appendicisporites tricornitatus (ARN-01). (O) Cyathidites minor (ARN-02). (P) Inaperturopollenites dubius (ARN-04). (Q) Classopollis sp. (ARN-02). (R) Araucariacites hungaricus (ARN-01). (S) Eucommiidites minor (ARN-01). (T) "Liliacidites" minutus (ARN-01). (U, V) Theriosynoecum cf. fittoni (Limnocytheridae): (U) Right lateral view, female carapace (AR-1-OS-001); (V) Left lateral view, male carapace (AR-1-OS-002). (W–BB) Rosacythere denticulata (Limnocytheridae): (W) Female? carapace, right lateral view, variant with extremely small rosette ornamentation (simply reticulated form) (AR-1-OS-006); (X) Male carapace of the variant with well-developed rosette ornamentation, left lateral view (AR-1-OS-011), and detail of the ornamentation; (Y) Female carapace of the variant with well-developed rosette ornamentation, left lateral view (AR-1-OS-007); (Z) Female carapace of the variant with strongly developed rosette ornamentation and spine-like nodes, left lateral view (AR-1-OS-015), and detail of the spine-like node ornamentation; (AA) Female carapace of the variant with well-developed rosette ornamentation, dorsal view (AR-1-OS-012); (BB) Female carapace of the variant with strongly developed rosette ornamentation and spine-like nodes, dorsal view (AR-1-OS-018), showing intraspecific variability. (CC), (DD) Cypridea cf. clavata (†Cyprideidae): (CC) Specimen in right lateral view (AR-1-OS-004); (DD) Specimen in left lateral view (AR-1-OS-005). (EE) Mantelliana sp. (Cyprididae) (AR-1-OS-003), right lateral view. Scale bars, 0.5 mm (A–J), 0.25 mm (K), 0.2 mm (L, U–EE), 0.01 mm (M–S), and 0.005 mm (T). See also Supplementary file 1.
![](https://iiif.elifesciences.org/lax/72477%2Felife-72477-fig5-figsupp1-v1.tif/full/617,/0/default.jpg)
Additional charophyte (A–J), palynomorph (K–P), and ostracod (Q–Y) records sampled from level AR-1 of Ariño.
(A, B) Atopochara trivolvis var. trivolvis (†Clavatoraceae) lateral views (AR-1-CH-003 and AR-1-CH-006, respectively); cell lettering after Grambast, 1968. (C–E) Clavator harrisii var. harrisii (†Clavatoraceae): (C) Lateral view (AR-1-CH-010); (D) Abaxial view morphotype I (AR-1-CH-012); (E) Abaxial view morphotype V (AR-1-CH-016). (F–J) Morphotypes of the abaxial part of the utricle of Clavator harrisii var. harrisii: (F) Morphotype I showing the impression of the phylloid cortical cells (phy), two intermediate cells (i) and an adaxial fan with five cells, two lateral cells (a and b) and three apical cells (c, d, e); (G) Morphotype II showing the adaxial fan with six cells by subdivision of the a cell; (H) Morphotype III showing the adaxial fan with seven cells by subdivision of a and b cells; (I) Morphotype IV showing an adaxial fan with eight cells by subdivision of d cell in addition to the other subdivisions already found in morphotype II, fusion of fan cells and intermediate cells is also observed; (J) Morphotype V with the same number of fan cells as in morphotype IV but showing different cell shapes and no fusion between intermediate and fan cells. (K) Trilobosporites purverulentus (ARN-02). (L) Laevigatosporites haardti (ARN-01). (M) Ceratosporites sp. (ARN-02). (N) Retimonocolpites dividuus (ARN-03). (O) Foraminisporis cf. undulatus (ARN-01). (P) Tricolpites sp. (ARN-04). (Q–Y) Rosacythere denticulata (Limnocytheridae): (Q–U) Variant with well-developed rosette ornamentation: (Q–S) Female carapaces, right lateral views and detail of the ornamentation (AR-1-OS-008, AR-1-OS-009 and AR-1-OS-010, respectively); (T) Male carapace, dorsal view (AR-1-OS-013); (U) Female carapace, ventral view (AR-1-OS-014); (V–Y) Variant with well-developed rosette ornamentation and spine-like node: (V, W) Female and male carapace respectively, right lateral views (AR-1-OS-016 and AR-1-OS-017, respectively); (X) Female carapace, dorsal view (AR-1-OS-019); (Y) Female carapace, ventral view (AR-1-OS-20). Scale bars, 0.05 mm (A–E), 0.01 mm (K–P), and 0.2 mm (Q–Y).
![](https://iiif.elifesciences.org/lax/72477%2Felife-72477-fig6-v1.tif/full/617,/0/default.jpg)
Formation of the amber deposit of Ariño.
(A) Idealised diagrams depicting (1) the original depositional environment (a, carbonates; b, soil prior to tree installation); (2) resiniferous forest installation and pedogenesis; concentration of in situ kidney-shaped resin pieces produced by the roots in a root horizon (b’); accumulation of aerial resin pieces fallen from the branches and trunk and a few resin pieces dragged after transport (wavy arrow) in a litter horizon (c); and (3) fossil diagenesis of the resin pieces, resulting in a layer containing strictly in situ autochthonous kidney-shaped amber pieces produced by roots (b’’), and a layer mostly composed of strictly ex situ autochthonous-parautochthonous aerial amber pieces and a few potentially allochthonous amber pieces (c’); level AR-1 corresponds to a single cycle of forest floor installation-destruction. (B) Artistic reconstruction of the coastal freshwater swamp ecosystem of Ariño, with emphasis on the depositional environment of the resin. The resiniferous trees are araucariaceans (extant model used: Agathis australis), tentatively identified as the resin source of Ariño; other depicted terrestrial plants are undetermined vegetation included for artistic purpose. Charophytes and a crocodile (Hulkepholis plotos) inhabit the shallow water body on the right; two nodosaurids (Europelta carbonensis), an iguanodontian (Proa valdearinnoensis), and a turtle (Aragochersis lignitesta) are shown on land; these vertebrate species were erected based on the Ariño bonebed material. Artist of the illustration in (B): José Antonio Peñas.
Videos
Tables
Reagent type (species) or resource | Designation | Source or reference | Identifiers | Additional information |
---|---|---|---|---|
Chemical compound, drug | BSTFA + TMCS, 99:1 | Merck/Supelco | ||
Chemical compound, drug | Dichloromethane Optima for HPLC and GC | Fisher Scientific | ||
Chemical compound, drug | Methanol Optimafor HPLC and GC | Fisher Scientific | ||
Software, algorithm | ImageFocusAlpha v. 1.3.7.12967.20180920 | Euromex | ||
Software, algorithm | Adobe Photoshop CS6 | Adobe Systems | RRID:SCR_014199 | |
Software, algorithm | Agilent MassHunter Quantitative Analysis B.06.00 | Agilent | RRID:SCR_015040 | |
Software, algorithm | Microsoft Excel v. 16.0.14131.20278 | Microsoft Corporation | RRID:SCR_016137 |
Additional files
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Supplementary file 1
List of palynomorphs recorded from the lower Albian bonebed level AR-1 of Ariño and their relative abundances.
ARN-01 and ARN-02 were obtained from the lower root layer with kidney-shaped amber pieces, and ARN-03 and ARN-04 from the upper litter layer rich in aerial amber pieces, all of them within the level AR-1. See also Figure 5 and Figure 5—figure supplement 1.
- https://cdn.elifesciences.org/articles/72477/elife-72477-supp1-v1.xlsx
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Transparent reporting form
- https://cdn.elifesciences.org/articles/72477/elife-72477-transrepform1-v1.docx