July 7, 2022 | David F. Coppedge

Dinosaur Convergence Loses Its Grasp

It looks like a T. rex but it wasn’t, they say;
Darwin Flubber rescues the tale.

 

Patagonia is a long way from Montana. In 2012, researchers discovered a large theropod dinosaur resembling a T rex in Patagonia, along with several sauropods. They’ve been excavating, cleaning and classifying it for a decade, deciding where and when it evolved into its niche in Darwin’s fallen tree (see 29 June 2022). Notably, this large predator had a big head, small arms, and strong hind limbs like its more famous lookalike. How did it get that way? Answer: Darwin Flubber did it! Our Darwin Dictionary defines Darwin Flubber as

a magical elastic substance made of a secret blend of Emergence, Convergence and Submergence. Darwin Flubber allows the Evolutionary Web of Belief to absorb any falsifying blow. Emergence allows creatures to arise further back in time than previously thought by supplying googols of beneficial mutations to the theory on demand. Convergence allows the web to reshape itself with new connections when similar fossils appear out of order. And Submergence is a cloaking substance that allows the keepers of Darwin’s Web of Belief to hide vulnerable parts of the web from the public.

And now, the dinosaur.

Source paper: Canale et al., “New giant carnivorous dinosaur reveals convergent evolutionary trends in theropod arm reduction,” Current Biology, 7 July 2022 (open access).

credit: Carlos Papolio

They named the beast Meraxes gigas after a dragon in Game of Thrones. The authors spend most of their time on getting the right mix of Darwin Flubber. In particular, as shown in the title, they focus on the Convergence ingredient. Since T. rex and this beast, on a different phylogenetic branch in their classification scheme, ended up with small arms, it must have happened by “convergent evolution.” They mention convergence no less than 20 times in the paper.

Meraxes documents convergent evolution of short arms among megapredatory theropods.

That’s the main Flubber component this time. Emergence is also a necessary ingredient in the potion, because this beast “emerged” 20 million Darwin Years before T. rex. And don’t forget the tincture of Submergence required to keep the press in line. No reporters dared to question the tale. They were ready. They all conspired to wait till the end of the embargo to post their own versions of the same explanation (7 Feb 2013).

A new giant dinosaur gives insight into why many prehistoric meat-eaters had such tiny arms (University of Minnesota, 7 July 2022).  This article refers to convergence without using the word: “the researchers found that large, mega-predatory dinosaurs in all three families of therapods grew in similar ways, it says. “As they evolved, their skulls grew larger and their arms progressively shortened.” Why that happened has been “the topic of much speculation and debate.” So where, exactly, was the “insight” into “why” this happened as promised in the headline? The answer is, “whatever.” The empty speculation sounds Lamarckian (use and disuse):

“What we’re suggesting is that there’s a different take on this,” Makovicky said. “We shouldn’t worry so much about what the arms are being used for, because the arms are actually being reduced as a consequence of the skulls becoming massive. Whatever the arms may or may not have been used for, they’re taking on a secondary function since the skull is being optimized to handle larger prey.”

Meraxes gigas was a huge dinosaur with tiny arms like T. rex (New Scientist, 7 July 2022). Reporter Corryn Wetzel was also shy about using the term “convergent evolution” but got the idea across anyway, letting an ‘expert’ say it in scholarly language:

Like T. rex, M. gigas had sharp teeth, possessed a large head and tail and walked on two powerful legs. “For a long time, we thought it was mostly tyrannosaurs that did the big head, long legs, small arms thing,” says James Napoli at the American Museum of Natural History in New York, who wasn’t involved in the research. This fossil reveals that another group of dinosaurs called carcharodontosaurs, which includes M. gigas, was also doing the same kind of evolutionary trend, he says.

Giant meat-eating dinosaur had a fancy skull and wee arms like T. rex (Live Science, 7 July 2022). This reporter comes out and names the Convergence ingredient in the magic potion. “Though Meraxes and T. rex both had wimpy-looking front limbs, they are not close relatives; instead, this trait is an example of convergent evolution — when distantly related species evolve similar features, Canale said.” The reporter can escape with, ‘he said it, not me.’

New giant carnivorous dinosaur discovered with tiny arms like T. rex (Cell Press via Phys.org, 7 July 2022). This article mentions two possible functions for the short arms, which were surprisingly muscular: holding onto a mate, or getting up from a prone position. Whatever. “T. rex and M. gigas evolved to have tiny arms independently,” the article says.  Why would that be? Well, stuff happens.

The authors first set the record straight; T. rex did not get their short arms from M. gigas or vice versa. Not only did M. gigas become extinct almost 20 million years before T. rex became a species, but they are also very far apart on the evolutionary tree. “There is no direct relationship between both,” says Canale. Rather, Canale believes that having tiny arms somehow gave the two dinosaurs some kind of survival advantage.

The lesson is not to become big headed: “for dinosaurs like M. gigas and T. rex, the larger their heads were, the smaller their arms became.”

The Dino That Looked T. Rex-y Long Before T. Rex  (The Scientist, 7 July 2022). Reporter Shawna Williams is the only one so far who doesn’t use or imply the term “convergent evolution.” She quotes Canale who thinks the short arms had some kind of function. At the end of the article is this humble quote: “‘Every new, weird, unexpected dinosaur is really important in reminding us just how much is left to be discovered,’ Napoli tells New Scientist.” Good for Napoli and Williams.

Back to the Paper: Is Convergence a Scientific Explanation?

The convergence explanation for three assumed lineages of theropods with short arms draws on similarities between individuals under the assumption of evolution by natural selection. It is a complex inference, not a straightforward explanation:

This remarkable degree of convergence provides evidence that forelimb reduction was actively selected for in multiple lineages of large predatory theropods that independently evolved to occupy a distinct limb-size morphospace region (Figure 4B). Although all three short-armed lineages together define their own region of this morphospace, it is worth noting that there is little overlap between them. Much of the variance within and between these clades is observed in femur length, which is a proxy for body size, rather than relative limb proportions, which track within a narrow range (0.6 > forelimb/femur > 0.4) (Figures 4B and 4C). This lack of overlap between the three groups suggests that the forelimb reduction is not simply a result of a common allometric pattern with arm reduction tracking absolute body size, but rather represents a suite of similar though not necessarily identical allometries. It is worth noting that the early diverging members of Abelisauroidea and Allosauroidea, including Eoabelisaurus, Concavenator, and Allosaurus, are more closely clustered in morphospace than are the later-diverging members of either lineage, or later diverging tyrannosaurids for that matter. This variance is at least partially explained by clades evolving smaller forelimb/femur ratios over time somewhat independent of size as, for example, demonstrated by the proportionately shorter forelimb of Meraxes when compared to Acrocanthosaurus, although both were very similar in size.

The idea is that a big head for a predator reduces the need for big limbs; Meraxes could do with its jaw the work that its limbs would have done. If this were a law of nature, it wouldn’t have so many exceptions. Polar bears have big heads and big arms; so do lions. Praying mantises are fierce predators but have small heads and big arms. As for reptiles, snapping turtles and komodo dragons haven’t learned to converge on big heads and tiny limbs. The quotes from the press releases make it clear that the authors are simply guessing. The authors are not sure. In the paper, they say,

Historically, there has been great interest in inferring the potential functions of the proportionately diminutive limbs in large theropods like T. rex, with interpretations including reproductive behavior, body support when an animal is rising from a prone position, or predatory behavior. Other authors have considered the forelimbs of tyrannosaurids and abelisaurids as vestigial with limited or no function, whereas a third school of thought has been to distinguish the question of function in individual species from macroevolutionary processes that may account for arm reduction in these species perhaps as a result of selection for other traits.

The authors “converge” on this latter explanation but are just speculating. Without live dinosaurs to study, who can know how these mighty creatures used their small forelimbs? The notion that creatures “evolve to occupy a distinct morphospace” commits a foul in Darwinian theory. Nothing “evolves to” do anything. Meraxes did not tell its DNA, “Hey, guys, I’m stuck in a morphospace. Can you find a chance mutation that will reduce my arms and make my head bigger? Oh—and be sure to send it into my gametes. It won’t help me but might help my kids.” That’s ridiculous. Evolution is a post-hoc fallacy; an observation after the fact that is attributed to the assumption of evolution.

One other flaw in the paper is worth mentioning: the authors use a metric called “Pagel’s Lambda” to infer degrees of relatedness. This article on Evolution News points out that Pagel’s Lambda is a circular argument that does not measure what its proponents think it does. What this means is that much of the apparent rigor in the paper is built on a foundation of sand.

Soft Tissue, Anyone?

The head was decorated with “unique protuberances and rugosity patterns on the dermal cranial bones.”
Credit: Jorge Gonzalez

None of the popular articles mention soft tissue found in the fossil, although New Scientist speaks of it being “exquisitely preserved.” It was so well preserved, in fact, that individual growth rings are found in some of the bones. Is it not surprising for bones said to be 90 million Darwin Years old to be so well preserved? Burrowing organisms typically make quick work of strata and fossils in a process well known as bioturbation. Look what the authors found when they cut open some bones. Watch for the words “primary” and “tissue” even though they are aware of the degrading activities of bacteria and fungi:

Osteohistological thin-sections were produced from a wedge of the rigth [sic] femur (taken on the anterior at approximately mid-shaft), a transverse section of the fibula (at minimum circumference), a transverse section of a dorsal rib fragment, and a transverse section of a small gastralium fragment.

In the fibula (Figure S3A), very little primary tissues remains visible, and at least 3-4 generations of secondary osteons are identifiable in the inner cortex. An EFS is visible in the periosteal margin, but otherwise no growth marks are identifiable (with their record erased through tissue remodeling). The femur wedge section (Figure S3B) preserves a transect of cortex from the periosteal to endosteal margin. The inner ¼ of the cortex is moderately remodeled, with primary tissue still visible in places but otherwise replaced with secondary osteons. In the remaining ¾ of the section where primary bone tissue predominates, it is consistent with fibrolamellar bone as a woven-parallel complex. The vascular patterns and density in the primary bone of the femur vary from laminar to plexiform arrangement over most of the cortex, particularly in the inner cortex, grading later into a mixture of plexiform to reticular in areas of the outer cortex, before reducing complexity in the outermost cortex. No inner circumferential layer is preserved. An external fundamental system (EFS; also known as an outer circumferential layer) is present in the periosteal margin, indicating skeletal maturity. The femur preserves 24 annual growth marks in the primary cortex, and an additional 4 in the EFS. At least one growth mark in the primary cortex is a ‘double LAG’ (i.e. ‘split LAG’, ‘couplet’, etc), and was counted as a single growth mark for aging purposes. There are additional features in the inner cortex that may represent growth marks / annuli, but which could not be determined confidently due to the degree of remodeling. A mixture of primary and secondary tissue is observed in the sectioned dorsal rib. The rib section of MMCh-PV 65 (Figure S3C) preserves approximately 8 observable growth marks, though they cannot be effectively traced around the circumference of the section due to the combination of remodeling and extensive taphonomic alteration/staining, the latter previously referred by other authors to be the result of fungal or bacterial activity.

These observations (see Figure S3 in the Supplemental Material) should be noted as possibly the key to the story. Such exquisite preservation of primary material argues against millions of years. If the bones are far younger than that, the entire “convergent evolution” tale, with all its assumed ancestors and phylogenetic diagrams, comes crashing down.

The bones are brute facts that deserve attention; the “convergent evolution” Flubber is smeared over it like whitewash, concealing the problems with how these mighty dinosaurs got the way they are. Everyone is going to have difficult observations to explain—creationists as well. Why would a designer make beasts that large with such small arms, and do it repeatedly in different places? No one questions the success of these creatures in their ecological circumstances. The supreme fitness of organisms to their environments makes sense only in a design worldview.

As stated above, organisms cannot “evolve to” become something by corralling rare beneficial mutations on demand. ICR is developing a model they call Continuous Environmental Tracking (CET; hear podcast Part 1, Part 2), where organisms were created with built-in mechanisms for adapting to their environment. That would be a design feature for robustness in a changing world. Researchers at ICR are taking an engineer’s perspective to identify these mechanisms, which may include coding, epigenetics, horizontal gene transfer and other observable phenomena.

In this view, organisms are driven to adapt from the inside out, not from the outside in. This is a causal theory that is testable and makes predictions. It does not throw up its hands and say, “Stuff happens.” It can account for many of the so-called “microevolutionary” differences within species (e.g., Darwin’s finches) and genera and in some instances within families, but it never crosses the higher boundaries. Granting selection to the environment is a mystical, magical notion guilty of the personification fallacy. CET views organisms as active, living, well-regulated agents making targeted changes from engineering principles inherent in them. Moreover, they can do it quickly, without requiring millions of years. Since evolutionists are giving up on the idea that Darwinism explains biology (29 June 2022), keep an open mind for this new perspective that promises better explanatory power.

 

 

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