Introduction

As you likely know, Pixel recently released a theropod hybrid Hel claimed to "destroy the current meta." I will be putting this claim, and others made in the doc to the test. This is her doc for anybody who would like to fact-check me. I will be more scrutinous here as I expect a lot from Pixel as he is a well-known creator and I know he is capable of making good hybrids. I would also like to bring this discussion here to a place we both have access to, as I have been informed that Pixel has been "debunking" some of my claims on the Titan Games Discord server, which I am banned from.

What Is Done Well

1. Great art, as always.
2. The doc is well-written and informationally dense.
3. Many very good design concepts such as focusing on rotational inertia
4. It's a solid, well-rounded hybrid, with a few very important tweaks.

The Big Problem

The biggest problem in Hel by far is the inclusion of the belgian blue cattle. The thing about the Belgian Blue is its incredible muscle is caused by a single gene. This incredible muscle, however, is a huge problem. Its muscles are large but its tendons and blood flow do not compensate and the muscles end up being incredibly stiff and inefficient. That much added muscle to a theropod at all would make it incredibly sluggish and would likely lead to agility and durability problems. But it's not just more muscle; the muscle does not have the tendons or the blood flow required to function correctly. And on top of that, the muscle is not hypertrophied; it's hyperplastic. Hypertrophied muscles have larger individual cells, which is the most efficient way to grow large muscles, as they get much stronger and waste less volume and mass on the connections between the cells and such. If Hel had this mutation which gets rid of myostatin, she would absolutely be entirely hanked.

And unlike many traits, with the Belgian Blue you cannot take only part of it or localize it. Myostatin is systemic and produced by the endocrine system. You can't select which muscles get it and which muscles don't. And it's also only one gene; you can't turn off a certain number of these genes and turn on some others. It's one gene. A single gene will always have 2 copies. That leaves 3 options. Either Hel has 0 copies, 1 copy, or 2 copies. 0 copies wouldn't make any sense, as if it were 0, Belgian Blue wouldn't have been included in the genome. So the question is between 1 copy and 2 copies. Both of which are bad and would negatively affect the hybrid. 2 copies would literally cause it to die from the heat while its muscles suffocated from a lack of blood flow. At that scale it is impossible to survive with such hyperplastic muscles. 1 copy, however, while it would certainly not benefit the hybrid, might not kill it. When an animal has one copy of the gene, it looks much more normal, as it still has some amount of myostatin to inhibit muscle growth. But the same exact problems are still there just on a lesser scale. It may be possible for Hel to survive if she only has one copy of the gene. Of course, the best course of action would be to remove the belgian blue from her genome entirely.

But as she is currently, she is on a very thin line between being functional and nonfunctional and she certainly wouldn't be capable of combat either way. It is a super easy fix to just remove it. For the rest of this analysis, I will act as if it is removed because it would be exhausting and meaningless for me to repeatedly mention the problems it causes alongside each other problem.

Medium Problems

The following are things that are certainly going to be physically problematic for the hybrid but won't cause it to be fully nonfunctional.

The Tail

The tail is a good attempt at making an advanced system but it falls short. Pixel claims the tail system will give Hel both agility and speed. That is wrong. Hel's tail is using the Carnotaurus to uptilt the transverse process (the things that stick out the side) to 75 degrees. That is relatively unclear depending on if it's 75 degrees from the normal angle of the transverse process or from the spinous processes. I will assume from the spinous processes, as that would be better for Hel and it seems that's what Pixel means in his doc since he said "as opposed to the usual angle of 90 degrees." The issue with that, which Pixel is aware of, is that that takes away space for the epaxial muscles, which are essential for holding up the tail voluntarily. Without these, the tail would need to be stiff to support its own weight which would reduce agility significantly as seen in Carnotaurus. Hel attempts to solve this problem by adding raised neural spines. There are a few issues with this. The biggest issue is he doesn't actually have raised neural spines. Nothing in his genome has muscular raised neural spines at the distal segments of the tail. He notes Shantungosaurus and Stegosaurus as to providing these spines but neither has raised neural spines at the distal segments of the tail. You can see this clearly from how thin they get when you reach the tip of the tail; that is because they attach tendons, not muscles. They are not strong enough to handle the force from the weight of the tail. Even if he did have sufficiently strong raised neural spines, they would significantly increase rotational inertia and would likely be even worse for agility than if the tail were simply made stiff. You also can't just have the spines at the tail base, as they do not have the leverage needed to hold up the tail.

A viable solution to this problem would be to have the transverse processes uptilted near the base of the tail, where the epaxial muscles could be attached to the raised neural spines without creating huge rotational inertia problems and where it doesn't have much effect if the tail is stiff. Then for the more distal segments of the tail, reduce the angle of the transverse process and make the tail less stiff. That way you can get the caudofemoralis muscle where it counts the most (the tail base) while maintaining the flexibility where it counts (the distal segments of the tail.)

The Armor

Contrary to Pixel's claims, the earless monitor lizard does not have "lightweight" armor by any stretch of the imagination. The percent weight claims are completely baseless and do not make any sense. I will not make any solid claims on the weight of the armor but a pure guess would put it near 20%. These lizards are known for being sluggish and relatively immobile. Their armor is also simple bone and keratin. There is no advanced material science there that would suggest it's any more efficient in terms of durability than something like a crocodile or any other armored lizard. This armor is very heavy and would likely lead to poor agility and heat issues. Even if it's scaled down, it's simply not efficient compared to something like fish scales or other advanced materials. And Hel is also said to have crocodile scutes. I won't get into the issues of having both of these in the skin at once but that will make Hel even heavier.

The Stamina

I will not go into detail in this section on the things reducing stamina; those have been mentioned in the sections on the armor and the Belgian blue. However, I will describe why the contributions for stamina are contradictory and will cause problems for power. The blue wildebeest is not some magical force. If you could truly have both power and stamina to that degree, every single animal on earth would have evolved that system. There is always a tradeoff. Wildebeest sacrifice peak force for stamina. In a muscle you only have so much room. That room could be spent on myofibrils or on mitochondria; both are very large. Of course you can improve stamina in some ways without making your hybrid weaker but everything comes with tradeoffs.

Small Problems

The following problems are problems that don't impact the hybrid too much but are just incomplete research or redundant contributors.

1. Multiple contributors are stated to in some manner "reinforce the limb bones." It is unclear which contributors reinforce what and why all of them are necessary.
2. A "strong fibrolamellar cortex" literally means nothing. A fibrolamellar cortex is used to see the growth of a dinosaur. Having a "strong" one would typically just mean that the dinosaur grew quickly and healthily.
3. Apatosaurus did not have a "wide epiphysis." "Epiphysis" is a word for the round part of a long bone. Assuming that is referring to the limb bones, apatosaurus did not have that nor would you even want that in a hybrid.
4. All vertebrates have hyaline cartilage. Joints already have hyaline cartilage. The tiger shark doesn't do anything for hyaline cartilage. Fibrocartilage is a thing used by many weight-bearing animals in their joints but that is also present in a lot of animals, including humans, in the spine.
5. There are 3 crocodiles doing almost identical things.
6. Caracal does nothing. It doesn't have stronger arms than xenosmilus and it can't provide any adaptations to the arms that will improve the strength over xenosmilus.
7. A longer ilium does pretty much nothing other than add weight, as the weight can already be supported with the current ilium.
8. The thagomizer is adding nothing but a little extra weight. Unless you count looking cool.
9. The ostrich does not "improve PCSA." PCSA stands for Physiological Cross-Sectional Area. Those are a bunch of big words that mean the cross-sectional area perpendicular to the muscle fibers relative to the length. PCSA is completely dependent on the muscle and is fundamentally reciprocal to the length of the muscle. The ostrich is not well known for having short muscles nor would that be a benefit.