Fig 1.
(A) Geologic map of Haţeg Basin (based on [20] and references therein). (B) Detailed geological map of the Vălioara area showing the main vertebrate sites (based on [20]. Base maps were compiled using openly licensed (CC BY 4.0 or public domain) datasets: Sentinel-2 (Copernicus, 2023.01.08), SRTM (NASA/JPL-Caltech), EU GISCO (Eurostat), and EU-Hydro (Copernicus/EEA).
Fig 2.
Site K2, Vălioara (Densuș-Ciula Formation).
(A) Status of the investigated bonebed in 2019 (B) and in 2022. (C) Vertically oriented tree trunk in the bonebed horizon of site K2. (D-F). In situ well-preserved dinosaur bones at site K2. (G). In situ associated pelvic elements of Rhabdodontidae indet. [12].
Fig 3.
Geological background and sedimentology of site K2.
(A) Sedimentary architecture, depositional environments and depositional units of the lower Densuș-Ciula Formation in the Vălioara area, for details see [20] (Bas.: basal deposits, Fluv.: fluvial deposits). (B) Sedimentary log of the K2 site, with important surfaces and sample locations. (C) Lower portion of the K2 outcrop showing structureless black and grey mudstone. (D) Texture of the heterolithic bonebed, plant fragments and molluscs.
Table 1.
Results of the geochemical analyses (TOC, TS and n-alkanes) on sample 6B, site K2, Vălioara, Densuș-Ciula Formation.
Fig 4.
Selected terrestrial palynomorphs, freshwater algae, and typical constituents of organic matter recognized at site K2, Vălioara (Densuș–Ciula Formation).
(A) Deltoidospora australis (sample 6B). (B) Polypodiaceoisporites sp. (sample P2). (C-D) Polypodiaceoisporites sp. (sample 6B). (E) Polypodiaceoisporites hojrupensis (sample 6B). (F) Laevigatosporites ovatus (sample 6B). (G) Lusatisporites dettmanniae (sample 6B). (H) Echinatisporis sp. (sample 6B). (I) Stereisporites antiquasporites (sample 6B). (J) Inaperturopollenites dubius (sample 6B). (K) Pinuspollenites sp. (sample 6B). (L) Classopollis sp. (sample 6B). (M) Araucariacites australis (sample 6B). (N) Oculopollis praedicatus (sample P2). (O) Trudopollis nonperfectus (sample P2). (P) Proteacidites sp. (sample 6B). (Q) Plicapollis serta (sample 6B). (R) Pseudopapillopollis praesubhercynicus (sample 6B). (S) Trudopollis minimus (sample 6B). (T) Myricipites bituitus (sample 6B). (U) Subtriporopollenites anulatus (sample P2). (V) Chomotriletes fragilis (sample P2). (X) Ovoidites sp. (sample 6B). (Y-Z) Pterodinium cingulatum cf. granulatum (sample 6B; reworked). (AA) large lath-shaped opaque phytoclasts (sample P2). (AB) a mixture of equidimensional opaque and translucent phytoclasts (sample 6B). (scale bar: 30 µm).
Fig 5.
Gas chromatogram–mass spectrometry spectra from sample 6B, site K2, Vălioara (Densuş–Ciula Formation) (A), and diverse cross-plots: C, D. phytane/n-C18 versus pristane/n-C17 indicating the type of organic matter and depositional environment.
(B) fragment of large-sized leaf cuticle considered to be composed mainly of long-chain n-alkanes (n-C23 – n-C31).
Fig 6.
Shells of the terrestrial and freshwater gastropods from site K2, Vălioara (Densuș–Ciula Formation).
(A) Lymnaeidae sp. (abapertural view). (B) Acroloxus sp. (apical view). (C) Physidae sp. 1 (apertural view). (D) Physidae sp. 2 (lateral view). (E) Physidae sp. 3 (abapertural view). (F) Physidae sp. 4 (apertural view). (G) Physidae sp. 4 (abapertural view). (H) Physidae sp. 4 (lateral view). (I) Physidae sp. 4, specimen2 (apertural view). (J) Physidae sp. 4, specimen2 (abapertural view). (K) Ajkaia sp. (abapertural view). (L) Pupinidae sp. 1 (lateral view). (M) Pupinidae sp. 1 (abapertural view). (N) Pupinidae sp. 1 (apical view). (O) Pupinidae sp. 2 (lateral view). (P) Pupinidae sp. 2 (enlarged view of the protoconch and the initial whorls of the teleoconch). (Q) Pupinidae sp. 2 (lateral view). (R) Laminiferinae sp. (abapertural view). (S) Laminiferinae sp. (lateral view).
Fig 7.
Shells of terrestrial gastropods and freshwater bivalves from site K2, Vălioara (Densuș–Ciula Formation).
(A) Lychnus sp. (apical-dorsal view). (B) Lychnus sp. (apical view). (C) Helicoidea sp. 1 (lateral view). (D) Helicoidea sp. 1 (apical view). (E) Helicoidea sp. 2 (apical view). (F) Helicoidea sp. 3 (apical view). (G) Helicoidea sp. 3 (lateral view). (H) slender gastropod sp. 1 (dorsal view). (I) slender gastropod sp. 2 (abapical view). (J) slender gastropod sp. 2 (apertural view). (K) slender gastropod sp. 3 (lateral view). (L) Sphaeriidae sp. 1. (M) Sphaeriidae sp. 2. (N) Cyrenidae sp. (O) Sphaeriidae sp. 3.
Fig 8.
Isolated vertebrate remains, site K2, Vălioara (Densuș–Ciula Formation).
(A) Lepisosteiformes indet., scale LPB [FGGUB] v.900 in external view. (B) Albanerpetontidae indet., right dentary LPB [FGGUB] v.901 in lingual and (C) labial views. (D) Barbatteidae indet., maxilla LPB [FGGUB] v.902 in lingual and (E) labial views. (F) Velociraptorine dromaeosaurid tooth, LPB [FGGUB] R.2885 in labial and (G) lingual views. (H) Richardoestesia sp. tooth, (LPB [FGGUB] R.2884) in labial and (I) lingual views. (J) Hadrosauroidea indet. right dentary fragment LPB [FGGUB] R.2887 in medial view. (K) Possible pterosaurian limb bone fragment LPB [FGGUB] R.2891. (L) Kogaionidae indet., left P1 (LPB [FGGUB] M.1710) in lingual and (M) oblique occlusal views.
Fig 9.
Isolated crocodyliform teeth, site K2, Vălioara (Densuș–Ciula Formation).
Doratodon sp., anterior-middle maxillary/dentary tooth (LPB [FGGUB] v.910) in (A), labial, and (B), lingual views. Doratodon sp., posterior maxillary/dentary tooth (LPB [FGGUB] v.907) in (C), labial, (D), lateral, and (E) lingual views. Theriosuchus-like taxon, caniniform premaxillary/anterior maxillary/dentary tooth (LPB [FGGUB] v.915) in (F), labial, (G), lateral, and (H), lingual views. Theriosuchus-like taxon, hypertrophied caniniform?maxillary tooth (LPB [FGGUB] v.924) in (I), labial, and (J), lingual views. Theriosuchus-like taxon, middle-posterior maxillary/dentary tooth (LPB [FGGUB] v.918) in (K), labial, and (L), lingual views. Allodaposuchus sp., apical part of anterior maxillary/dentary tooth (LPB [FGGUB] v.911) in (M), labial, (N), lateral, and (O) lingual views. Allodaposuchus sp., posterior maxillary/dentary tooth (LPB [FGGUB] v.913) in (P), labial, (Q), lateral, and (R) lingual views. Acynodon sp., anterior maxillary/dentary tooth (LPB [FGGUB] v.885) in (S), labial, (T), lateral, (U), lingual, and (V) apical views; arrow in S, U and V point to the lateral platform (pf) replacing the carina basally. Acynodon sp., middle-posterior maxillary/dentary tooth (LPB [FGGUB] v.906) in (X), labial, (Y), lateral, and (Z), lingual, views. Acynodon sp., posterior maxillary/dentary tooth (LPB [FGGUB] v.903) in (AA), labial/lingual, and (AB) apical views. Indeterminate crocodyliform morphotype (?Acynodon, or perhaps?juvenile Allodaposuchus – see text for details), probably middle-posterior maxillary/dentary tooth (LPB [FGGUB] v.920) in (AC), labial, (AD), lateral, and (AE), lingual views.
Fig 10.
Generalized cranial and skeletal reconstruction of the ‘K2 rhabdodontid’, Vălioara (Densuș–Ciula Formation).
(A) Associated premaxillae, LPB (FGGUB) R.2769 in left lateral view. (B) Right maxilla, LPB (FGGUB) R.2770, in lateral view. (C) Left prefrontal, LPB (FGGUB) R.2772, in dorsal view. (D) Articulated right frontal-postorbital, LPB (FGGUB) R.2774, in dorsal view. (E) Right dentary, LPB (FGGUB) R.2778, in medial view. (F) Middle dorsal vertebra, LPB (FGGUB) R.2795, in posterior view. (G) Chevron, LPB (FGGUB) R.2805, in anterior view. (H) Right scapula, LPB (FGGUB) R.2806, in lateral view. (I) Left ulna, LPB (FGGUB) R.2807, in medial view. (J) Right ilium, LPB (FGGUB) R.2809, in lateral view. (K) Left ischium, LPB (FGGUB) R.2810, in lateral view. (L) Left tibia, LPB (FGGUB) R.2812 in lateral views. (M) Right fibula, LPB (FGGUB) R.2814, in medial view. (N) Third metatarsal, LPB (FGGUB) R.2816, in lateral view. (O) Pedal phalanx, LPB (FGGUB) R.2822, in dorsal view. Shaded skeletal elements indicate bones represented in the K2 assemblage (adapted from [12]).
Table 2.
Skeletal parts and taxon representation in the site K2 vertebrate assemblage.
Table 3.
NISP and MNI values as well as fragmentation rate associated with taxa in the K2 assemblage.
Table 4.
Recovery rate of the different skeletal elements in the K2 assemblage.
Table 5.
Skeletal completeness in the K2 assemblage: %TC – represents the percentage of total skeletal completeness; A – the actual number of skeletal elements recorded from site K2; E– the expected number of elements in a complete skeleton; %R – recovered element percentage of a certain skeletal element.
Fig 11.
Generalized skeletal reconstruction of the ‘K2 titanosaur’, Vălioara (Densuș–Ciula Formation).
(A) Dorsal vertebra LPB (FGGUB) R.2896, in anterior view. (B) Partial sacral ribs LPB (FGGUB) R.2897, in dorsal view. (C) Anterior caudal vertebra LPB (FGGUB) R.2715, in ventral view. (D) Articulated anterior mid caudal vertebrae LPB (FGGUB) R.2715, in left lateral view. (E) Posterior caudal vertebra LPB (FGGUB) R.2898, in left lateral view. (F) Chevron LPB (FGGUB) R.2899, in anterior view. (G) Right humerus fragment LPB (FGGUB) R.2900, in anterior view. (H) Metapodial element LPB (FGGUB) R.2091, in lateral view. (I) Right pubis fragment LPB (FGGUB) R.2902, in lateral view. (J) Fragmentary left femur LPB (FGGUB) R.2903, in posterior view. (K) Right femur LPB (FGGUB) R.2904, in posterior view. (L) Fragmentary and crushed right femur LPB (FGGUB) R.2905, in posterior view. (M) Right??tibia fragment LPB (FGGUB) R.2906, in lateral? view. (N) Right fibula LPB (FGGUB) R.2907, in lateral view. (O) Pedal phalanx LPB (FGGUB) R.2908, in dorsal view. Shaded skeletal elements indicate bones represented in the K2 assemblage (based on the generalized skeletal reconstruction of a Transylvaninan titanosaur from [5]).
Fig 12.
Relative abundances of the vertebrate taxa in site K2, Vălioara (Densuș–Ciula Formation).
(A-B) NISP and (C) MNI distributions.
Fig 13.
Relative abundances of the skeletal elements in the K2 vertebrate assemblage.
(A) Different skeletal parts and (B) Voorhies Groups.
Fig 14.
Bone representation by size in the K2 assemblage.
(A) Size distribution of bones based on (A) bone volume (B) maximum dimension bones and bone fragments and (C) complete and reconstructed skeletal elements.
Fig 15.
Bone surface modifications recorded.
Distribution of abrasion based on total (A) and NISP assemblage (B). Distribution of weathered bones in the site K2 assemblage based on total assemblage.
Fig 16.
Fracture patterns of skeletal elements.
Bone breakage distribution based on (A) total and (B) NISP assemblage. Distribution of breakage types (C) in the total and (D) the NISP assemblage.
Fig 17.
Reconstruction of the depositional processes producing the studied fossiliferous sedimentary sequence at site K2, Vălioara (Densuș–Ciula Formation).
Stage 1: Formation of the lake and deposition of black/grey mudstone from suspension settling in a quiet environment. Stage 2: Fluvial flood transporting coarser material, plants and vertebrate remains in the dominantly muddy lake. TS. - taphonomic set (see text for details). Stage 3: Peak flooding event burying the fossil-bearing bed with sandstone. Subsequently, renewed suspension settling (see Stage 1) dominates deposition until the next flood.
Fig 18.
Stratigraphic position of site K2 (Neagului Valley, Vălioara – red star), Middle Member of the Densuș-Ciula Formation, relative to other important uppermost Cretaceous Transylvanian vertebrate sites (grey stars), including those mentioned/discussed specifically in the text (stars outlined in red), from the Hațeg (A – Sibișel Valley section, B – Râul Mare section, and C – Pui section) and southwestern Transylvanian basins (updated and modified from [3,20]); note that, as already acknowledged by [3], the relative positions of the sites within the different lithostratigraphic units is reliable, albeit not always precisely established, whereas that between these units is largely tentative.
For the definitions and lithological make-up of the sedimentary units (units 1.1 to 2.3) separated in the lower part of the Densuș-Ciula Formation around Vălioara, see [20]. Abbreviations of localities and sites: I, II, VI - Kadić’s sites I, II and VI, Vălioara; Bo – Boiţa; CM – Ciula Mică; Cr – Crăguiș; D1 - Densuș; GB – General Berthelot; K1, K2, K5, K6 - sites K1, K2, K5 and K6, Vălioara; Lc – Lancrăm; Li – Livezi; NV – Nălaţ-Vad (several different sites); Nvs – New Vertebrate Site, Vălioara; ODA – Oarda de Jos (several sites); ODAN – Oarda de Jos, microvertebrate lens; ODAS – Oarda de Jos, ‘Stocks’ accumulation; PD – Pui Depozit; PS – Pui Swamp; PT – Petrești (different other sites); PT – 0/a - Petrești, level 0/a; PT – 0/c - Petrești, level 0/c; PT – 1a - Petrești, level 1a; Pu – Pui (several different sites); RL – Râpa Lancrămului; RR – Râpa Roșie; SbG – Sebeș-Glod; SFH – Secaș Feţii Hill; SC – Sânpetru Cărare; SG – Sânpetru Groapă; SS – Sânpetru Scoabă; ST – Sânpetru Terminus; Tc – Teleac; To – Totești-Baraj (several different sites); Tu – Tuștea-Oltoane; VB – Vălioara Budurone; VF1 – Vălioara Fântânele 1; VF3 – Vălioara Fântânele 3; Vu – Vurpăr (for references regarding these sites, see text); ‘?’ marks tentative (i.e., not well constrained) position of sites/boundaries.