#middle jurassic

[knuppitalism-with-ue]

Result from the Tiaojishan Formation stream, or rather Yanliao biota stream. This incredible assemblage was on my mind from the very start of doing these pieces, not just because it has tons of fascinating critters but because a big portion of the vertebrates here appear...

to have been at least partially arboreal. Tons of small pterosaurs, feathered dinosaurs, mammals and even a few lizard show adaptations for living in the canopy. With weirdos like Yi or at least two lineages of gliding mammals. Few formations offer a glimpse into this world...

that is usually omitted from the fossil record. The outcrops of the Tiaojishan Formation and the rest of the Yanliao biota are known from Northern China, especially Liaoning but also Hebei and Inner Mongolia. These incredibly well preserved fossils were preserved in lakes in...

which fine volcanic ash quickly covered up carcasses. The surrounding forests have been assumed to be subtropical for a while but a new publication actually even compares them with tropical moist montane forests. The flora was dominated not by conifers but Bennettitales which...

made up more than 30% of the flora. These plants, that were probably close to angiosperms, had flower like organs and give this forest a little more color. Besides that we have ginkgos, ferns and other gymnosperms. But the true diversity lies with the inverts...

Over 700 species have been described so far (here only a selection), often with color preservation articulated bodies. We also have bizarre leaf mimics, giant fleas and the largest mesozoic spider, Mongolarachne. When it comes to the vertebrates an interesting aspect is the very small fish...

assemblage, with two lampreys and one or two ray-finned fishes. Instead a large diversity of salamanders filled many aquatic niches and a docodont with beaver tail joined them too. On land, small dinosaurs and mammals can be found. So far missing are any really large animals probably due to a taphonomic bias for small animals to be preserved more easily. The vertebrate size chart is a collaboration between me and Discord member Avery, who also did the inverts. Plants where assembled by JW.

Full size can be seen here: https://drive.google.com/drive/u/0/folders/1X_ypdI4M00FkkVSr6lKImNEZzS-BCjK2

[saritapaleo]

Archovember 2025 Day 7

Dinosaur Spicomellus afer, of Middle Jurassic, Morocco!

Initially described and named in 2021 based on a single rib with fused osteoderms, Spicomellus afer set the paleontological community ablaze this past year when more material was found. This new material revealed that the animal would have had a unique array of spines over its body, including extremely elongated neck spines, as well as spines on its tail, making it the oldest known ankylosaur with a tail weapon. Even the original rib that was once Spicomellus’ only known fossil is unique, as its spikes are fused directly to the bone, a trait not known in any other vertebrate. Despite all this prickly, seemingly defensive weaponry, it’s more likely that Spicomellus’ long neck spines evolved for display, similar to the antlers of a deer, with defense being their secondary purpose.

Ankylosaurs are thought to have eventually taken the place of the Jurassic stegosaurs, but the discovery of Spicomellus places the rise of ankylosaurs further back in the Jurassic. In the El Mers III Formation of Middle Jurassic Morocco, Spicomellus would have actually lived alongside at least two stegosaurs: Adratiklit and Thyreosaurus. This indicates that the two major thyreophoran groups (Ankylosauria and Stegosauria) coexisted for more than 20 million years, at least in this locality. Spicomellus would have also encountered the sauropod Turiasauria. Other dinosaurs in this formation have thus far been fragmentary.

This art may be used for educational purposes, with credit, but please contact me first for permission before using my art. I would like to know where and how it is being used. If you don’t have something to add that was not already addressed in this caption, please do not repost this art. Thank you!

[qarkudon]

[paleonativeart]

Day 2: Maiopatagium furculiferum.

An extinct genus of gliding euharamiyids which existed in Asia during the Middle-Late Jurassic period.

[makairodonx]

Jurassic June 2024 Day 14: Epidexipteryx hui

[new-dinosaurs]

Alpkarakush kyrgyzicus Rauhut et al., 2024 (new genus and species)

(Postorbitals [bones in the skull behind the eyes] of Alpkarakush kyrgyzicus [scale bar = 5 cm], from Rauhut et al., 2024)

Meaning of name: Alpkarakush = large mythical bird from the Epic of Manas; kyrgyzicus = from the Kyrgyz Republic

Age: Middle Jurassic (Callovian)

Where found: Balabansai Formation, Jalal-Abad, Kyrgyzstan

How much is known: Partial skeletons of two individuals, together including parts of the skull and limbs, as well as some vertebrae. Some isolated teeth and a wishbone from the same locality may also belong to this species (and possibly to one of the aforementioned individuals).

Notes: Alpkarakush was an allosauroid, a group of medium-sized to large theropods that also includes Allosaurus and Giganotosaurus. More specifically, it was a metriacanthosaurid, a lineage of allosauroids known mostly from the Jurassic of Eurasia. The bones in its skull forming the back rim of the eye socket exhibit prominent projections and a rough surface texture, suggesting that they may have supported keratinous display structures overhanging its eyes.

The type specimen of Alpkarakush is estimated to have been about 7–8 m long in total body length and to have weighed about 1.2 tons. Based on microscopic examination of their bone structure, the type specimen was at least 17 years old and close to fully grown when it died, whereas the second partial skeleton found alongside it belonged to a smaller, younger individual. The describers of Alpkarakush consider it plausible that the two individuals were associating with one another before they died.

(Schematic skeletal of Alpkarakush kyrgyzicus showing known bones [scale bar = 1 m], from Rauhut et al., 2024)

Reference: Rauhut, O.W.M., A.A. Bakirov, O. Wings, A.E. Fernandes, and T.R. Hübner. 2024. A new theropod dinosaur from the Callovian Balabansai Formation of Kyrgyzstan. Zoological Journal of the Linnean Society 201: zlae090. doi: 10.1093/zoolinnean/zlae090

[mirkokosmos]

Lorrainosaurus

[fundinofactoftheday]

Dinofact #62

All known pachycepahlosaurs, except for two species, Ferganocephale and Stenopelix lived during the late Cretaceous. Ferganocephale, which can be traced back to the middle Jurassic, lacks some features on its teeth distinctive to all other known pachycephalosaurs, and Stenopelix, traced to the early Cretaceous, is based on a partial skeleton lacking the skull, which some scientists have now reclassified as a ceratopsian. With both outlying species of pachycephalosaurs sometimes considered nomen dubiums, it is possible that all known pachycephalosaurs lived during the late Cretaceous period.

Source: Wikipedia [1], [2], [3]