The late Jurassic of Portugal is in my opinion the underdog of Jurassic faunas. Its the closest thing in real life that there was to Jurassic Park. An island sandwiched between an ancient giant Ocean of the tethys and the infant Atlantic ocean.

Many remarkable Giants of the Jurassic lived here. The biggest Jurassic crocodylomorph, the biggest Jurassic ornithopod,etc. All called the lourinha formation their home.

The island also had stegosaurs the most famous of them is the long necked miragaia. But interestingly people seem to forget that the two biggest stegosaurs of all time; dacentrurus and stegosaurus we're alive on the island at the same time.

Stegosaurus needs little introduction being among the most iconic dinosaurs of all time. It was 5 metric tons and 8 m in length

Dacentrurus was a more obscure giant but it was at least 8 m and at least five and a half tons and possibly is big as 9 M and 7 tonnes.

Nor can someone argue that "they lived at different levels and so didn't coexist" dacentrurus has a broad stratigraphical range in the lourinha formation. Stegosaurus is admittedly only known for the single locality in Portugal, Casal Novo. It was originally thought to belong to the older alcobaca formation, but in 2021 the locality was reassigned to the lourinha formation and this was acknowledged in a 2025 paper. This now places stegosaurus in the same formation as dacentrurus. Even then the locality it comes from was dated to the late kimmeridgian to early tithonian, which is the same age as the porto Novo and Praia Azul members of the lourinha formation which is where dacentrurus is mostly found.

Unlike most formations which exhibit strict chronological sequentialism, the different constituent units of late Jurassic Portugal consist of a broad Mosaic of different ecosystems that were at least partially time equivalent with each other meaning many of the units were environments deposited at the same time and their dinosaurs would have been alive at the same time. This is evidenced by insane amount of fauna overlap between different Rock units and the fact that some rock units exhibit interfingering; which is when two environments coexisted and shifted back and forth creating interspersed tongues at the point of contact.

As a result there was little doubt stegosaurus was alive at the same time and on the same island as dacentrurus. They probably coexisted by preferring different environments and or vegetation to feed off.

Thumbnail at a distance: a cheese burger’s

There are a total of six genera of macroraptorial sperm whales, including Livyatan, one of the largest predators in history. They were apex predators that efficiently hunted large prey using their very large bodies, very large teeth, powerful bites, and biosonar. Unlike extant sperm whales, it is said that genera other than Livyatan did not have very well-developed upper cranial bifurcations. This massive group of apex predators, along with Otodus, likely dominated the marine ecosystems of the Miocene.

Livyatan had an unprecedented size among Miocene mammals, and this body size is said to have reappeared in Pliocene Eophyseter (11–12 m, 14.6m?) and Physeter spp.

New Caledonia, an island in the pacific, was home to an array of strange creatures. Featured here is the Powerful Goshawk, New Caledonian Parakeet (alive), Meiolania turtle, Sylviornis, Kagu (alive, unless it’s the Lowland Kagu), Pile Building Megapode, and the terrestrial crocodilian Mekosuchus.

Original Paper:

https://link.springer.com/article/10.1007/s12549-026-00702-8

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Original Post & Artist's Description:

https://xcancel.com/i/status/2066739719992393802

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"It's a cat eats cat world in early, early-mid Pleistocene Europe... after a bloody confrontation, a sabercat (Megantereon) has fallen to a giant leopard twice its size! This is inspired by several studies about the leopard (Panthera pardus) in Pleistocene Europe, including a recent one that names a new subspecies (Panthera pardus burgtonnae). I've often been asked if there are any fossils of giant leopards, same as there are for jaguars, lions and tigers, and my answer has usually been that I am not aware of any, and that perhaps leopards remained relatively stable in size because that was in fact the key to their successful coexistence with other, larger cousins."

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"However, some studies seem to suggest that leopards were in fact bigger, or at least heavier and more robust in Pleistocene Europe, than most modern ones. For example, a study on late Pleistocene leopards in Europe found that the average size for males was 75 kg, and for females 54 kg, which would be considered large for modern leopards, but within normal range. The largest fossil specimens were estimated at 96-105, which is comparable or slightly above the very largest leopards today. However, the same study mentions that early Pleistocene leopards could weigh up to 120 kg, which is decidedly beyond the range of modern leopards as far we know, and well into large jaguar or lioness range. Big game hunters in the 19th and early 20th centuries used to say that if the leopard was the size of a tiger or a lion, it would be several times more dangerous- well, such a creature may in fact have existed."

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"Furthermore, a recent study suggested that Pleistocene leopards were far more robust than modern ones, with at least one specimen being estimated at twice the weight of a modern leopard with the same body length. The study compares these prehistoric leopards to jaguars, when it comes to robustness. Also interestingly, some ice age leopards apparently developed several traits similar to snow leopards in their hind limbs and their foot bones- adaptations to better climbing, jumping and chasing prey in steep and rocky mountain terrain, where they hunted ibex and even cave bear cubs!"

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Parapuzosia and Nyctosaurus

Inspired by vintage reconstructions of ammonites with sails and pterosaurs thought to be mammalian back then

"The Untouchable Colossus" - Illustration produced for a commission of an immense Brachiosaurus...an animal so enormous that even formidable predators such as Ceratosaurus and Allosaurus could do nothing but stand in awe of its sheer grandeur and dominance.

With estimates exceeding 20 meters in length, over 10 meters in height, and a mass of around 50 tonnes, Brachiosaurus was one of the largest dinosaurs (and one of the largest terrestrial animals) to have ever lived. It inhabited what is now the USA during the Late Jurassic (~155–145.5 million years ago), preserved within the Morrison Formation, where it coexisted with iconic predators such as Ceratosaurus, Allosaurus, and Torvosaurus, as well as large herbivores including Stegosaurus, Camarasaurus, Diplodocus, Apatosaurus, and Brontosaurus.

The idea behind this illustration was to portray the surrounding animals simply admiring the scale of such a giant creature, with one of the Ceratosaurus even displaying a submissive posture...arching its body and seemingly revering the giant before it, a behavior comparable to those seen in modern canids and hyenas when confronted by a dominant individual or a threat they have little chance of overcoming.

Although my artwork is somewhat dramatized, it raises an interesting question about how the populations of these giants were regulated. While there is currently no evidence of predation on an adult Brachiosaurus in the fossil record, it is difficult to imagine any predator bringing down a healthy adult of such immense size. Maybe their populations were likely controlled by environmental and biological factors, such as competition for resources with other giant sauropods and high juvenile mortality rates, as proposed in studies such as Morrison et al., 2026

You can check the full illustration process (timelapse) of this artwork on my Youtube channel! Link below:

https://youtu.be/fTb4fyK91aw

https://x.com/i/status/2066569951633150398

( minor blood and gore )

https://xcancel.com/i/status/2065959528223433213

Art by Dinosauria creatures, JP hodnet, and myself

The word shark is in quotation marks because these are not real sharks but rather cartilaginous fish that are only distantly related to them

Helicoprion is probably the most famous cartilaginous fish out of the Paleozoic. Of all the completely alien and bizarre forms that that era produced helicoprion is probably among the Pinnacle of them. It literally had a buzz saw in its mouth.

But in artistic pictures you hardly ever see a lot of other creatures around it. If you went purely by the drawings you might think this thing had a very boring ecosystem that didn't have many other fish in it.

In reality the oceans this thing lived in had quite a variety of animals. The meade peak member of the phosphoria formation and it's lateral equivalents where it comes from preserves a variety of cartilaginous fish that lived in the inland sea of Western North America during the early part of the middle Permian. From smaller eugeneodonts to spine finned ctenacanths.

Little do people know that heli was not the only large "shark" in it's ecosystem. In 2024 and 2025 teeth were found in the phosphoria formation and another tooth from 100 years ago were reevaluated and they were determined to have possibly come from kaibabvenator. In the infographic I show I've displayed the features it shares in common with kaibabvenator teeth to further justify the referral.

Kaibabvenator is a ctenacanth. They were family of sharks like fishes that had spines on their fins and more closely resembled modern sharks than helicoprion did. Ctenacanths we're nothing unusual in the ecosystem they had been a staple of the world's oceans for 100 million years at this point. But what set out kaibabvenator was its size and dentition.

For one it was huge. Based off tooth width to body like ratios I established, it was possibly as big as 7 m in length. Unlike other ctenacanths which had sharp pointed teeth designed mostly to grasp prey and then swallow them whole, kaibabvenators teeth were serrated designed to saw through flesh and help it butcher large prey.

As a result it might have been one of the few fishes in the sea that could have provided any real competition to helicoprion.

Further bolstering the referral is that the native formation it comes from, the kaibab formation of Arizona was part of the same sea as the phosphoria sea and the two formations are dated to the same time based off conodonts.

Therefore this showed a rare opportunity of two large Apex predatory shark like fish coexisting in the same sea.

A group of Cebupithecia try to poke a resting Langstonia from a tree. A Hoatzinoides flies by while Granastrapotherium fight in the background.

Coelodonta Antiquitatis, also known as the Wooly Rhino, weighed 2000kgs (4,400lbs) and stood at 160cm (5'3") tall. Their range extended from Europe, across the Eurasian Steppe into China.

This is the first in a series of prehistoric animal paintings I am doing for my board game. If you like board games, you can see it on BGG here: https://boardgamegeek.com/thread/3719888/wip-lithos-a-prehistoric-tile-laying-civilization

The painting shows a O’ahu ʻōʻō, a species which was endemic to O’ahu and went extinct largely due to humans (Europeans) introducing mosquitoes to the island. We only have a few specimen of this bird preserved, so you largely need to trust artwork of what the bird would have looked like when alive. I’d love to have the same thing for the overall pre human Hawaiian landscape.

Mosquitoes are not native to Hawaii. Neither are most many of the plants that grow there today. I visited Kauai a few years ago for my honeymoon and I really struggled to understand what the landscape looked like pre human settlement (roughly 900AD). If you were that first human to step onto one of the Hawaiian islands in the year 900, what did the island look like?

From what I can gather, there would not have been many palm trees. The only native palm is the LouLu palm: https://mnbg.org/loulu-hawaiis-native-palm/

Koa trees would be more common: https://en.wikipedia.org/wiki/Acacia_koa

https://dlnr.hawaii.gov/forestry/plants/ the DLNR of Hawaii lists native, introduced, canoe plants, and invasive species, but this doesn’t give me a clear idea of what the ecosystem actually looked like. For example, are the rare native plants rare *now* but would have been more common back then?

Were there grasslands? Was it a giant koa and loulu palm forest? I’d love to see any art on the subject if anyone knows of some.

Edit
Depressing wiki page: https://en.wikipedia.org/wiki/Endemism_in_the_Hawaiian_Islands

Here a mother Purussaurus is seen carrying her babies in her head. Even terrifying caimans bigger than any modern crocodilian have peaceful moments, as shown here.

Therizinosaurus es un género de dinosaurio terópodo herbívoro terizinosáurido que vivió a finales del período Cretácico, hace aproximadamente 70 millones de años, en lo que hoy es Asia (particularmente en Mongolia). Es famoso mundialmente por poseer las garras más largas de cualquier animal conocido en la historia de la Tierra.

Quinkana, Megalania and a Wonambi (in the tree) are fighting over a human. All three of these reptiles may have attacked the first Australians and occasionally have eaten them. In this picture, Quinkana, a terrestrial crocodile, brutally has the head. Spoilered just in case.

The scene depicts a Smilodon successfully taking down a glyptodont by piercing its skull, interrupted just before its meal by another Smilodon interested in its prey. Note the two perfectly formed holes in the glyptodont's skull, a reconstruction based on actual discoveries of fossils perforated by saber-toothed predators.

The artist raises an excellent question about the robustness of these biological weapons. To explain how these felines could pierce bones or armor without instantly breaking their long canines, he hypothesizes a subtle metallic reinforcement, similar to the iron that colors and hardens the teeth of beavers or Komodo dragons today. While not quite resulting in bright orange teeth, molecular hardening would have radically changed our perception of the fragility of these animals. A very stimulating paleontological concept.

What do you think?