They have a mosaic of traits that makes pinning down their phylogeny difficult

Think of it this way:

You have an evolutionary tree of a bunch of species, which I’ll refer to with numbers. These species have traits, which I’ll refer to with letters.

Species 1 has traits A B C D E F G H

Species 1 branches off into two new species, 2 and 3

2 has since lost trait A and trait H

3 has lost trait G

That’s fairly easy to plot at this point, you have 1 branching into 2 and 3

Okay now let’s say 3 has branched into two new species, 4 and 5

4 has now lost A and H

5 has lost A

If all we have is the species and their traits, and no knowledge of how this evolution occurred, then it’s very hard to tell if species 4 evolved this way:

All traits - lost A and H - lost G

Or

All traits - lost G - lost A and H

When you broaden the scale out to dozens of taxa and hundreds of traits

It gets even more muddled

Phylogenetics goes off of the simplest possible (within reason, insert asterisks here) tree to produce the taxa with the traits as they are recorded, but simplest isn’t always how it goes

Taxa can revert, too, regaining traits they’ve lost, whether through mutation or gene expression

Convergent evolution and reversals make all of this even more muddled

An easy example: Humans, Chimps, and Gorillas

Humans share unique traits with chimps that gorillas don’t have

But we also have traits that gorillas have that chimps don’t

And chimps and gorillas have traits that humans don’t

So how do we know chimps are closer to humans than gorillas?

The *percent* similarity

The number of traits gorillas have exclusively in common with chimps or with humans

Is MUCH less than the number of traits humans have exclusively in common with chimps

Hence the tree has gorillas branching off first, with chimps and humans as sister taxa

Megaraptors are a relatively recently known group of dinosaurs with a lot of fragmentary scattered remains and a mosaic of traits

So it’s hard to pin down what the simplest tree is because of it

Boris and Dolores are gonna have a rough time taking Marinos down y'all. Also, WATCH THIS VIDEO MEGARAPTORS ARE SIIIIICK

And its a megaraptor!

Thoughts:

Megraptors are the most under-appreciated large theropods.

It's so nice to see pop science articles showing dinosaurs with feathers/fuzz now.

Its apparently mostly-complete, which is rare.

That pseudo-crocodile leg in its mouth isn't just an artist's imagination- it was actually found with a fossilized with a leg in its mouth.

Oh, and here's its thumb claw: