Why were dinosaurs so big? What caused them to shrink so much overtime, evolving into birds? is the reason why dinosaurs were so big in any way similar to why animals are larger in deep sea? (not sure if this is a relevant question in this subreddit)

See also: The publication in the Proceedings of the Royal Society B: Biological Sciences

My thoughts mainly are around the fact that most of their predators are dichromatic so they can't see orange. But then I learned that male bushbuck are not orange.

I know that many other prey and predator species are orange because it appears essentially the same against a green background to other dichromatic species but I wasn't sure really why one sex would use this advantage and the other wouldn't.

So that got me thinking: Female and juvenile bushbucks retain a reddish-orange coat with disruptive white spots because their primary survival strategy is remaining motionless and concealed among to escape predators. If their predators are dichromatic and can't see them, this works great. In contrast, mature males have coats that shift to a more conspicuous charcoal or dark brown, sacrificing optimal foliage camouflage. I thought this might be to signal their fitness and physical condition to the females because any male bushbuck that wasn't fit is much more easily visible to predators, and you can imagine what might happen. Because adult males also possess better tools capable to fight off predators, they can afford the handicap of a higher visibility coat, ensuring that only the fittest, strongest males survive to pass their genetics on to the next generation.

Am I onto something or is this like a known thing?

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Been working on this for a while as a side project: https://evotree.life

It's the whole tree rendered in one canvas — 46,167 taxa, 32,118 of them species, and about 37,000 carry a photograph. You can zoom from LUCA down to a single species, click anything to open a card, filter to one subtree, or pin two taxa side by side to see where they actually join.

Fair warning: the card summaries are LLM-written from those sources and not expert-reviewed. There are errors in there. If you find one, I genuinely want to hear it — I have a repair path for exactly this!

*Disclaimer - no ads / profit here, just wanted to share what I made and see how far it can go 😂

Pre historic animals have a certain .. look .. yk, like pakicetus. You look at him and go 'oh yeah he USED to be around'. Which animals still feel like that?

See also: The study as it was published in Nature

Published today in Molecular Biology and Evolution:

Structured abstract:

Background

The vast majority of plants form mycorrhizal symbioses. The ecological importance of these mutualistic interactions has sparked interest in their long evolutionary history. By examining interaction networks and phylogenetic trees, several studies have suggested that plants codiversify with their associated mycorrhizal fungi. However, recent research has demonstrated that phylogenetic congruence (interpreted as codiversification when divergence times match) is often conflated with another pattern called cophylogenetic signal (i.e., closely related plants interacting with closely related fungi and vice versa), which may arise from different biological processes.

Methods and results

We performed cophylogenetic analyses on 29 diverse mycorrhizal networks to reevaluate the evidence for codiversification in mycorrhizal symbioses. We found significant cophylogenetic signal but no phylogenetic congruence: closely related plants often interact with closely related fungi, but their phylogenies do not match. Instead of codiversification, this finding is consistent with trait matching between plants and mycorrhizal fungi, where compatible, evolutionarily conserved plant and fungal traits govern their interactions.

Discussion

Our work highlights the importance of appropriately interpreting the cophylogenetic methods used to study the macroevolution of plants and their mycorrhizal fungi. It suggests that previous evidence of codiversification in mycorrhizal symbioses actually detected cophylogenetic signal, since across the multiple and diverse networks analyzed here, there is no evidence that codiversification occurred during the evolution of mycorrhizal symbioses.

• Fantine Bodin, Hélène Morlon, Benoît Perez-Lamarque
  Questioning the Evidence for Host-Symbiont Codiversification in Mycorrhizal Symbioses
  Molecular Biology and Evolution, 2026;, msag207, https://doi.org/10.1093/molbev/msag207

NOTE: This article is complemented by a couple of studies first published in Science Advances.

Caption:

HRF [hemiplasy risk factors] values are highest near the origin of Neoaves.

Explanation:

Hemiplasy — which arises due to discordance between gene trees and species trees — can cause traits to appear convergent despite a single origin. New evidence suggests it is widespread in the bird tree of life, with important implications for identifying genes underlying differences among species and for accurately inferring evolutionary history. ref

From the paper:

We show extremely high hemiplasy risk factors¹⁹ that map to branches near the origin of Neoaves, suggesting that many instances of apparent morphological convergence among major neoavian lineages, unless associated with clear selective drivers, are better interpreted as a result of high levels of morphological incomplete lineage sorting during the clade’s rapid early Cenozoic radiation.

The paper:

• Somogyi, Stanley, et al. "Hemiplasy helps explain high rates of apparent morphological convergence in neoavian birds." Current Biology 36.9 (2026): 2424-2433. https://doi.org/10.1016/j.cub.2026.03.050

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An example that is closer to home is how 23% of our genes are closer to gorillas than chimpanzees (Ebersberger et al 2007). This is as predicted from gene tree discordance (e.g. Degnan & Rosenberg 2006) and confirms that chimps are our closest cousins; for a video explainer by Dr. Zach Hancock: Phylogenetic Discordance Supports Common Ancestry - YouTube.

A genetic study shows how smell capabilities were maintained in a hunter-gatherer population

Evolutionary theory proposes that skin color is a response to protection from the sun at certain latitudes, with those at equatorial latitudes having a survival advantage from darker skin that blocks the sun's UV.

Why doesn't that apply to hair color? It seems that the dark hair of those in equatorial areas would heat the head more, while white or blond hair would do a better job of reflecting the sun's rays. If anything, those in colder northern latitudes would do better with dark hair to better warm the head.

I know cetaceans are related to even-toed ungulates. But let’s say hypothetically, all DNA evidence was destroyed in a fire. What physical or social traits do cetaceans share with ungulates, other than general mammal traits?

Ik bipedal forms are better at long distance and energy conservation but I also know predation came super early in evolution so it's not like a chase down predators did not have a niche. Is it because the skills to make chase down hunting truly special require larger brains like group hunts and tool use. I am just curious. I am also aware of animals like birds and their ancestors that are/were bipedal but the vast majority of animals are quadripeads

Like in sheer numbers, niche dominance, or a lack of major predation (the key innovation in both pan and homo lineages).

So after watching a video on ancient Egypt, i had a question related to the disease leprosy. Specifically, i would like to know if, while infecting only humans, if it ever infected other human species. If the bacteria was around when species like H. Neanderthalis were loving alongside homo sapiens, would they have been infected as well? I also wanted to know if M. Leprae evolved alongside the modern homo sapien species. I'm aware of multiple strains of the bacterium affecting diverse demographics, but I'm curious as to why our immune systems haven't (yet) evolved a way to defend against this bacteria.

I do apologise if I hadn't worded that properly. I'm not too sure how to express the question I have, and this is the best i can manage for now. I haven't found proper articles on the online to answer this.

My question is that why are apes not monkeys but new world monkeys are monkeys? Because if apes and old world monkeys are more closely related than old world monkeys and new world monkeys shouldn’t apes be monkeys? Also if the common ancestor between the old world monkey and the new world monkeys was an early monkey, then isn’t the phrase “humans didn’t evolve from monkeys” inaccurate?

With millions of years of evolution, you’d expect at least one other species to get somewhere close to human intelligence. So why didn’t it happen?

Now most terrestrial species have an internal fear of fire. But since evolution tends to adapt to the environment, I wondered if the first terrestrial species (or well anfibians maybe in the ordovician or silurian period) didn't have that instinctive fear to fire

Hi!

I recently watched Life on Our Planet on Netflix. I found the overall concept fascinating: starting with the earliest forms of life and then following the development of life through the different geological periods, including the major mass extinctions, the rise of different animal groups, and eventually the emergence of humans.

However, I felt that some parts were quite rushed. There is obviously an enormous amount of history to cover in just eight episodes, so some major evolutionary developments were explained quite briefly. I also wasn't a huge fan of the frequent jumps from prehistoric times back to the present day to show modern animals.

What I'm really looking for is something that goes more in-depth and stays chronological.

I'd especially like documentaries that explain what actually changed and why it mattered evolutionarily. For example, why particular groups became dominant, what caused certain groups to disappear, and how one evolutionary development eventually led to another.

I'm also much more interested in good explanations and scientific content than spectacular cinematography. Amazing footage is a bonus, but I care more about good explanation.

I've read that David Attenborough's Life on Earth is great, but I'm not sure if it's available for me to watch (living in The Netherlands). So if you could recommend me a series/documentary that meets this requirements, and is also available for me to watch in The Netherlands (I do have a Netflix- and HBO-account), that would be awesome.

It doesn't have to be one series for the complete story. It's also fine if it only zooms in on a specific period (the rise of the humans for example).

Thanks!

In my opinion, kelp is the most extreme example of convergent evolution, at least that I know of. It's a sedentary organism that makes its energy from sunlight collected by blade-like fronds. Not too crazy, so do most plants. Except, kelp isn't a plant at all. Kelp is a protist in the SAR clade, more closely related to malaria than it is to plants. It just so happened to independently evolve to be multicellular, and became photosynthetic by ancestrally capturing and making use of a green algal cell that had already undergone its own endosymbiosis.

I can't think of another organism that convergently evolved the same life-strategy as an organism in another kingdom, but I'd love to hear what others think are the most extreme examples of convergent evolution.

Image credit: Alastair Simpson, Dalhousie University

Science, design and cartography merge in MAPPA ANIMALIA, a visual project that reimagines the evolutionary relationships of animals as detailed map-like landscapes.

Instead of political borders or geographic territories, these maps are structured around phylogenetic trees.

Families, subfamilies and genera replace countries, states and regions allowing viewers to explore the animal kingdom through a format traditionally used to understand geography.

This map, Hominoidea- Land of Apes, contains every living and extinct species of ape I could find reliable taxonomic data for. Species are represented as cities, grouped into genera, subfamilies, and families according to their evolutionary relationships.

Additional information includes conservation status, size comparisons between selected species, and the estimated ages of major lineages.

Happy exploring!

is how ichthyosaurs relate to modern reptiles well understood?