That's A Lot of Fish

Made a fake retrosaur for a design challenge.

The Marine Iguanodon or Rynchotitan 

A (previously thought to be) extinct species of gigantic fossil reptile belonging to the retrosaurian family, somewhat similar to iguanodon creatures previously classified. Its fossils discovered in late Cretaceous formations, this species is hypothesized to have lived throughout the South Pacific Ocean on landmasses such as New Guinea, New Zealand, and French Polynesia. A chance discovery by a submersible of partially uncovered remains within ocean sediment has lead paleontologists to surmise that this particular kind of retrosaur was aquatic. 

This was at least partially confirmed in the late 20th century when a colossal and severely mutated individual of this species apparently swam from the southern Pacific, trekked across Panama, swam through the Atlantic and made landfall on Manhattan island. The reason for this bizarre journey is unknown, thought it’s believed to be some exaggerated form of migration instinct amplified and altered by its mutation. 

It wasn’t too bad, really. At least, it wasn’t a ~huge~ disaster. It was kind of like having a moose in your driveway, a little scary, but it can be weathered with a bit of patience. Only on a city-sized scale, of course.

Baragon's Kids

So after being used for Frankenstein Conquers the World, the Baragon suit was used to make the monsters Pagos, Neronga, Gabora, and Magura for the Ultraman series. So it’s a little bit like he has descendants. Sea Baragon and 2001 Baragon are thrown in for good measure.

Godzilla-Raptor

Godzilla as a Dromaeosaur 

Don't get me wrong, feathers are an important part of depicting any kind of raptor, and most theropod dinosaurs. I just like the idea that being mutated by an atomic blast burned all his feathers off and they grew back sparsely and in weird ways.

Almost didn't do this one, on account of a Godzilla with raptor features could just end up being Zilla/Gino/Godzilla1998. Adding Godzilla's distinctive low center of gravity as well as (hopefully) appropriately positioned raptor arms helped move it along.

Plateo-Zilla

Godzilla as a Plateosaur.

One idea I've read is that Godzilla might be derived from some sort of carnivorous or omnivorous plateosaur, sort of like the inverse of therizinosaurs. An interesting idea.

I was surprised to learn while researching for this that prosauropods aren't really a scientifically classified clade anymore. They've been absorbed into the sauropodomorph suborder.

Cephalo-Zilla

Godzilla as a pacheycephalosaur. Godzilla is ostensibly a theropod dinosaur in some of the movies, so I thought it would be a nice exercise to apply Godzilla features of other families of dinosaurs.