TABLE S1. Calcareous nannofossils raw data (number of specimens in ~700 fields of view).
| Species | LV1 | LV2 | LV3 | LV4 | LV5 |
| Amphizygus brooksii | 0 | 2 | 1 | 1 | 0 |
| Amphizygus minimus | 0 | 1 | 0 | 1 | 0 |
| Arkhangelskiella cymbiformis | 1 | 0 | 1 | 0 | 2 |
| Biscutum constans | 1 | 0 | 0 | 0 | 0 |
| Broinsonia parca constricta | 0 | 0 | 0 | 1 | 2 |
| Broinsonia parca parca | 0 | 0 | 0 | 0 | 1 |
| Calculites ovalis | 0 | 1 | 0 | 0 | 0 |
| Chiastozygus amphipons | 0 | 1 | 2 | 1 | 3 |
| Chiastozygus bifarius | 0 | 0 | 0 | 2 | 1 |
| Chiastozygus litterarius | 0 | 1 | 0 | 0 | 0 |
| Cretarhabdus striatus | 0 | 0 | 0 | 0 | 1 |
| Cribrosphaerella ehrenbergii | 0 | 6 | 1 | 6 | 7 |
| Cylindralithus coronatus | 0 | 0 | 0 | 0 | 2 |
| Eiffellithus eximius | 3 | 7 | 5 | 9 | 11 |
| Eiffellithus gorkae | 0 | 0 | 0 | 0 | 1 |
| Eiffellithus turriseiffelii | 0 | 1 | 0 | 1 | 0 |
| Eprolithus floralis | 0 | 0 | 0 | 0 | 1 |
| Gartnerago segmentatum | 0 | 0 | 0 | 1 | 0 |
| Helicolithus trabeculatus | 0 | 1 | 0 | 1 | 1 |
| Lithastrinus grillii | 0 | 0 | 0 | 0 | 0 |
| Loxolithus armilla | 0 | 0 | 1 | 3 | 0 |
| Lucianorhabdus maleformis | 0 | 1 | 0 | 2 | 2 |
| Manivitella pemmatoidea | 0 | 0 | 0 | 1 | 1 |
| Micula staurophora | 1 | 3 | 2 | 3 | 3 |
| Placozygus fibuliformis | 0 | 0 | 0 | 1 | 0 |
| Prediscosphaera cretacea | 1 | 4 | 4 | 2 | 11 |
| Reinhardtites anthophorus | 1 | 5 | 0 | 0 | 1 |
| Retecapsa crenulata | 1 | 6 | 5 | 14 | |
| Rhagodiscus achlyostaurion | 0 | 2 | 0 | 0 | 0 |
| Russellia laswellii | 0 | 0 | 0 | 0 | 1 |
| Staurolithites sp. | 0 | 1 | 0 | 0 | 0 |
| Tranolithus orionatus | 1 | 6 | 2 | 2 | 3 |
| Watznaueria barnesiae | 10 | 39 | 33 | 19 | 73 |
| Watznaueria quadriradiata | 0 | 0 | 1 | 0 | 0 |
| Zeugrhabdostus bicrescenticus | 0 | 0 | 1 | 0 | 1 |
| Zeugrhabdotus diplogrammus | 0 | 1 | 2 | 0 | 0 |
| Total | 20 | 89 | 62 | 64 | 143 |
| Relative abundance | 0.02 | 0.13 | 0.09 | 0.09 | 0.21 |
TABLE S2. Dimensions of the measured ammonites.
| Specimen inventory number |
Dimensions | D | H | T | U | T/H | U/D | Figure 7 (in the main text) |
| NHMS 57406/LV5 | Dmax | 237 | 97 | 49 | 59 | 0.51 | 0.25 | Figure 7A-D |
| DPhragmocone | 214 | 106 | 44 | 34 | 0.42 | 0.16 | ||
| NHMS 56556/LV5 | DPhragmocone | 164.3 | 79 | ~46.2 | 29.8 | 0.58 | 0.18 | Figure 7E-H |
| DPhragmocone | 101 | 86.9 | – | 16.7 | – | 0.17 |
Notes: Dmax = shell measured at maximum diameter; DPhragmocone = shell measured at phragmocone; H = height of whorl; T = thickness of whorl; U = umbilicus; T/H = ratio of whorl thickness and whorl height; U/D = ratio of umbilicus and shell diameter.
TABLE S3. Source table used for the statistical analyses.
| No. | Taxon | LV1 | LV2 | LV3 | LV4 | LV5 |
| 1 | Amphizygus brooksii | 0 | 1 | 1 | 1 | 0 |
| 2 | Amphizygus minimus | 0 | 1 | 0 | 1 | 0 |
| 3 | Arkhangelskiella cymbiformis | 1 | 0 | 1 | 0 | 1 |
| 4 | Biscutum constans | 1 | 0 | 0 | 0 | 0 |
| 5 | Broinsonia parca constricta | 0 | 0 | 0 | 1 | 1 |
| 6 | Broinsonia parca parca | 0 | 0 | 0 | 0 | 1 |
| 7 | Calculites ovalis | 0 | 1 | 0 | 0 | 0 |
| 8 | Chiastozygus amphipons | 0 | 1 | 1 | 1 | 1 |
| 9 | Chiastozygus bifarius | 0 | 0 | 0 | 1 | 1 |
| 10 | Chiastozygus litterarius | 0 | 1 | 0 | 0 | 0 |
| 11 | Cretarhabdus striatus | 0 | 0 | 0 | 0 | 1 |
| 12 | Cribrosphaerella ehrenbergii | 0 | 1 | 1 | 1 | 1 |
| 13 | Cylindralithus coronatus | 0 | 0 | 0 | 0 | 1 |
| 14 | Eiffellithus eximius | 1 | 1 | 1 | 1 | 1 |
| 15 | Eiffellithus gorkae | 0 | 0 | 0 | 0 | 1 |
| 16 | Eiffellithus turriseiffelii | 0 | 1 | 0 | 1 | 0 |
| 17 | Eprolithus floralis | 0 | 0 | 0 | 0 | 1 |
| 18 | Gartnerago segmentatum | 0 | 0 | 0 | 1 | 0 |
| 19 | Helicolithus trabeculatus | 0 | 1 | 0 | 1 | 1 |
| 20 | Lithastrinus grillii | 0 | 0 | 1 | 0 | 0 |
| 21 | Loxolithus armilla | 0 | 0 | 1 | 1 | 0 |
| 22 | Lucianorhabdus maleformis | 0 | 1 | 0 | 1 | 1 |
| 23 | Manivitella pemmatoidea | 0 | 0 | 0 | 1 | 1 |
| 24 | Micula staurophora | 1 | 1 | 1 | 1 | 1 |
| 25 | Placozygus fibuliformis | 0 | 0 | 0 | 1 | 0 |
| 26 | Prediscosphaera cretacea | 1 | 1 | 1 | 1 | 1 |
| 27 | Reinhardtites anthophorus | 1 | 1 | 0 | 0 | 1 |
| 28 | Retecapsa crenulata | 1 | 1 | 1 | 1 | 1 |
| 29 | Rhagodiscus achlyostaurion | 0 | 1 | 0 | 0 | 0 |
| 30 | Russellia laswellii | 0 | 0 | 0 | 0 | 1 |
| 31 | Staurolithites sp. | 0 | 1 | 0 | 0 | 0 |
| 32 | Tranolithus orionatus | 1 | 1 | 1 | 1 | 1 |
| 33 | Watznaueria barnesiae | 1 | 1 | 1 | 1 | 1 |
| 34 | Watznaueria quadriradiata | 0 | 0 | 1 | 0 | 0 |
| 35 | Zeugrhabdostus bicrescenticus | 0 | 0 | 1 | 0 | 1 |
| 36 | Zeugrhabdotus diplogrammus | 0 | 1 | 1 | 0 | 0 |
| 37 | Taxon 1 | 0 | 0 | 0 | 0 | 0 |
| 38 | Taxon 2 | 0 | 0 | 0 | 0 | 0 |
| 39 | Taxon 3 | 0 | 0 | 0 | 0 | 0 |
| 40 | Taxon 4 | 0 | 0 | 0 | 0 | 0 |
| 41 | Taxon 5 | 0 | 0 | 0 | 0 | 0 |
| 42 | Taxon 6 | 0 | 0 | 0 | 0 | 0 |
| 43 | Taxon 7 | 0 | 0 | 0 | 0 | 0 |
| 44 | Taxon 8 | 0 | 0 | 0 | 0 | 0 |
| 45 | Taxon 9 | 0 | 0 | 0 | 0 | 0 |
| 46 | Taxon 10 | 0 | 0 | 0 | 0 | 0 |
| 47 | Taxon 11 | 0 | 0 | 0 | 0 | 0 |
| 48 | Taxon 12 | 0 | 0 | 0 | 0 | 0 |
| 49 | Taxon 13 | 0 | 0 | 0 | 0 | 0 |
| 50 | Taxon 14 | 0 | 0 | 0 | 0 | 0 |
| 51 | Taxon 15 | 0 | 0 | 0 | 0 | 0 |
| 52 | Taxon 16 | 0 | 0 | 0 | 0 | 0 |
| 53 | Taxon 17 | 0 | 0 | 0 | 0 | 0 |
| 54 | cf. Sphenopteris ungeri | 0 | 0 | 0 | 0 | 0 |
| 55 | Pachydiscus cf. haldemsis | 0 | 0 | 0 | 0 | 1 |
| 56 | Pirenella alvincziense | 1 | 0 | 1 | 0 | 0 |
| 57 | Pleurocera sp. | 1 | 1 | 1 | 0 | 0 |
| 58 | Pyrgulifera boeckhi | 1 | 1 | 1 | 0 | 0 |
| 59 | Campylostylus galloprovincialis | 1 | 1 | 1 | 0 | 0 |
| 60 | Neritoplica sp. | 1 | 0 | 0 | 0 | 0 |
| 61 | Parateinostoma sp. | 1 | 0 | 0 | 0 | 0 |
| 62 | Pirenella sp. | 1 | 0 | 1 | 0 | 0 |
| 63 | Cassiope obvoluta | 1 | 0 | 0 | 0 | 0 |
| 64 | Onkospira sp. | 0 | 0 | 0 | 1 | 0 |
| 65 | Melanopsis crastina | 1 | 1 | 1 | 0 | 0 |
| 66 | ?Rhabdocolpus sp. | 0 | 0 | 0 | 1 | 0 |
| 67 | Acteonoidea indet. | 0 | 0 | 0 | 0 | 1 |
| 68 | Pseudamaura alkenyeriensis | 0 | 0 | 0 | 0 | 1 |
| 69 | Trichotropis sp. | 0 | 0 | 0 | 0 | 1 |
| 70 | Ageria sp. | 0 | 0 | 0 | 0 | 1 |
| 71 | Voluthidae indet. | 0 | 0 | 0 | 0 | 1 |
| 72 | Acteonella renauxana | 0 | 0 | 0 | 0 | 1 |
| 73 | ?Nairiella sp. | 0 | 0 | 0 | 0 | 1 |
| 74 | Neritopsis spinosa | 0 | 0 | 1 | 0 | 0 |
| 75 | Deianira bicarinata | 0 | 0 | 1 | 0 | 0 |
| 76 | Venericardia sp. | 0 | 0 | 0 | 1 | 0 |
| 77 | ?Corbula sp. | 1 | 0 | 1 | 1 | 0 |
| 78 | ?Exogyra sp. | 0 | 0 | 0 | 1 | 0 |
| 79 | ?Platyceramus sp. | 0 | 0 | 0 | 0 | 1 |
| 80 | Granocardium sp. | 0 | 0 | 0 | 0 | 1 |
| 81 | Panopea sp. | 0 | 0 | 0 | 0 | 1 |
| 82 | Pycnodonte sp. | 0 | 0 | 0 | 0 | 1 |
| 83 | Pinna sp. | 0 | 0 | 0 | 0 | 1 |
| 84 | Anomiidae indet. | 0 | 0 | 0 | 0 | 1 |
| 85 | Hemiasteridae indet. 1 | 0 | 0 | 0 | 0 | 1 |
| 86 | Hemiasteridae indet. 2 | 0 | 0 | 0 | 0 | 1 |
| 87 | Asteroidea indet. | 0 | 0 | 0 | 0 | 1 |
| 88 | Cunnolites sp. | 0 | 0 | 0 | 0 | 1 |
| 89 | Aulosmilia sp. | 0 | 0 | 0 | 0 | 1 |
| 90 | aff. Lamniformes indet. | 0 | 0 | 0 | 1 | 0 |
| 91 | Paratrygonorrhina amblysoda | 0 | 0 | 0 | 1 | 0 |
| 92 | Atractosteus sp. | 0 | 0 | 1 | 0 | 0 |
| 93 | Lepisosteus sp. | 0 | 1 | 1 | 0 | 0 |
| 94 | Paralbula casei | 0 | 0 | 0 | 1 | 1 |
| 95 | Enchodus cf. petrosus | 0 | 0 | 0 | 1 | 0 |
| 96 | Paraplesiopoma transylvanica | 0 | 0 | 0 | 1 | 0 |
| 97 | ?Alytidae indet. | 1 | 0 | 0 | 0 | 0 |
| 98 | Anura indet. | 1 | 0 | 1 | 0 | 0 |
| 99 | Scleroglossa indet. | 1 | 0 | 0 | 0 | 0 |
| 100 | cf. Doratodon sp. | 0 | 0 | 1 | 0 | 0 |
| 101 | Allodaposuchidae indet. | 1 | 0 | 0 | 0 | 0 |
| 102 | Maniraptoran theropods | 1 | 1 | 0 | 0 | 0 |
TABLE S4. Source table for the distribution chart.
| Groups | LV1 | LV2 | LV3 | LV4 | LV5 |
| Meso and macroflora | 0 | 0 | 1 | 17 | 0 |
| Cephalopods | 0 | 0 | 0 | 0 | 1 |
| Gastropods | 9 | 4 | 8 | 3 | 6 |
| Bivalves | 1 | 0 | 1 | 3 | 7 |
| Echinoids | 0 | 0 | 0 | 0 | 2 |
| Asteroids | 0 | 0 | 0 | 0 | 1 |
| Corals | 0 | 0 | 0 | 0 | 2 |
| Insects ichnofossils | 0 | 0 | 0 | 2 | 0 |
| Elasmobranchii | 0 | 0 | 0 | 2 | 0 |
| Actinopterigii | 0 | 1 | 2 | 3 | 1 |
| Herpetofauna | 4 | 0 | 2 | 0 | 0 |
| Dinosaurs | 1 | 1 | 0 | 0 | 0 |
