Cratonavis zhui: A Dinosaur-like Bird?

A Mixed Evolutionary Bag

Cratonavis has some functions which are thought about more dinosaurian and less like modern-day birds in addition to some functions which supposedly bridge the space in between dinosaurs and birds and even in between Archaeopteryx (dated at 150 MY) and modern-day birds. Some of the most obvious distinctions in between Cratonavis and Archaeopteryx are the much shorter tail in Cratonavis, 4 digits on the foot (compared to 3 on Archaeopteryx) and the scapula and coracoid merged into a scapulocoracoid on Cratonavis however unfused in Archaeopteryx. This latter quality is a bit difficult as the merged scapulocoracoid is thought about a more primitive quality than what is discovered on the presumably 30 MY older Archaeopteryx.

In addition to having a more “primitive” function than its supposed forefather, Cratonavis likewise has some difficult physiological functions, a few of which it shows “direct ancestors,” confuciusornithids, and others which vary from even that “immediate ancestor clade.” For example, both groups have actually the merged scapulocoracoid and a pygostyle, which is a merged set of caudal vertebrae at the end of the tail. But Cratonavis has a toothed jaw, whereas the apparently somewhat older Confuciusornithidae (dated in between 131 and 120 MY) have no teeth. And the digit count in between the 2 clades likewise varies, with the Confuciusornithidae having just 3 digits on each foot (most modern-day birds have 4 toes, though a couple of [mostly flightless ones] have 3 and even 2 toes [e.g., ostriches]).

Cratonavis’ closest “sister clade” is Chongmingia, which likewise shares more “primitive” characteristics and contrasts more “modern” includes with Cratonavis. Chongmingia has a much smaller sized scapula (shoulder blade) however a longer thigh (upper leg bone) and humerus (arm bone). Perhaps most striking is the apparent existence of plumes for Chongmingia and no discernable ones for Cratonavis. And although plumes are discussed in the paper, there do not seem any conclusive plume impressions discovered with the animal. However, it is possible that poor conservation of the matrix surrounding Cratonavis is to blame. While it is hard to be sure, there might be some indicator of a minimum of the impression of plumes listed below the wing bones (on the best side) and the pygostyle—showing possible wing and tail plumes, respectively.

So, Cratonavis includes a mix of functions which the authors of the paper recommend:

displays a unique mix of a non-avialan dinosaurian akinetic skull with an avialan post-cranial skeleton, revealing the essential function of evolutionary mosaicism in early riser diversity.1

As among the earliest-branching pygostylians, jinguofortisids (~8 million years of duration for the recognized members) maintain a suite of distinct morphologies that is even more made complex by Cratonavis. Cratonavis has actually a greatly developed skull that is morphologically more like that of non-avialan theropods than a lot of simultaneous avialans….2

The mix of a non-avialan dinosaurian skull and avialan post-cranial skeleton recorded in Cratonavis contributes to the tally of examples where avialan development has actually been formed deeply by mosaicism.3

And as coauthor Dr. Zhonghe Zhou mentioned in a press interview, “The aberrant morphologies of the scapula and metatarsals preserved in Cratonavis zhui highlight the breadth of skeletal plasticity in early birds.”4

In other words, the phylogenies of Jurassic and Cretaceous birds (or non-birds) are developed based upon qualities which leap backward and forward in between more primitive and sophisticated functions amongst expected forefathers and descendants and can even change drastically amongst “sister clades” as talked about above. There is no specific physiological development from dinosaur to bird, just “plasticity.” For the obtained phylogeny list from the Cratonavis paper, see Fig. 1 listed below.5

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Fig. 1

Does Cratonavis Really Have a Dinosaurian Head?

If you examine the image of the fossil find, you’ll discover that the whole skull does not look total—the lower jaw is missing, however scientists discuss that they discovered structures of the lower jaw, so it appears that the lower jaw was compressed beneath the upper jaw. See likewise the artist’s impression here. While the journal paper is less mind-blowing than the popular science writeups (with one website declaring that Cratonavis’ “skull is almost the same as that of dinosaurs like Tyrannosaurus rex”6) they however declare that “Cratonavis has a heavily built skull that is morphologically more like that of non-avialan theropods than most contemporaneous avialans….”7

But how precise is this contrast? If the evolutionary dino-bird paradigm is removed away, does the real fossil represent a bird with the “dinosaurian head” overexaggerated or a dinosaur with the “birdlike body” qualities overexaggerated? The authors had the skull digitally rebuilded (Fig. 2 a and b) and likewise had an interpretative skull restoration (Fig. 2 e), which looks rather various from the digital restoration. See Fig. 2 listed below.

Fig. 2

A Matter of Definition

It is essential to comprehend that there are a great deal of terms and meanings utilized by the authors of Cratonavis’ paper that require attention. First, we require to comprehend that the word theropod has actually been altered due to the fact that of the impact of evolutionary concepts. Its very first meaning, produced in 1881 by Othniel Charles Marsh, organized all understood dinosaurs from the Triassic and the meat-eating dinosaurs from the Jurassic and Cretaceous. But in 1986, Jacques Gauthier provided a brand-new meaning for theropods through cladistics (an evolutionary approach that presumes origins) as a group of birds and all saurischians (dinosaurs).8 That is, prior to 1986, theropod implied a group of dinosaurs. After 1986, this term implies a group that consists of both birds and dinosaurs. Secondly, due to the fact that of evolutionary concepts, dinosaurs consist of bird dinosaurs (which they call birds) and non-avian dinosaurs (all the extinct dinosaurs aside from birds). So, when they state non-avian theropod, they indicate whatever from T. rex to oviraptorids, dromaeosaurids, and troodontids. That is, it is a variety of numerous various characteristics and animals that the term non-avian theropods does not truly state much about any particular function.

The Akinetic Skull

Despite the claim that researchers neutrally approach the information, this is never ever the case.

Kinesis relates to bone motions in the skull. These motions are necessary for the movement of the jaws that “increases the versatility and precision of biting, grasping, holding and swallowing of food items, as well as preening of the plumage.”9 Other authors concur, concluding that it “is present in most living birds, occurring in a variety of forms strongly associated with specialized feeding mechanisms.”10 That is, kinesis is associated with lots of functions essential for animal life. But due to the fact that evolutionists think that “The closest nonavian dinosaurian relatives of Aves are thought to have akinetic skulls with an unreduced palatal complex,”11 they primarily relate this function in the skull to origins, development, and the relationship in between birds and dinosaurs.

Despite the claim that researchers neutrally approach the information, this is never ever the case. There is no neutrality. We all have a worldview, a method of seeing and translating deep space around us. We all have presumptions, principles, and concepts that affect our analyses and conclusions. We can see that used in clinical documents really frequently. For example, the primary point of the paper is that Cratonavis zhui “exhibits a unique combination of a non-avialan dinosaurian akinetic skull with an avialan post-cranial skeleton….”12 This “unique combination” leads them to translate those functions as “revealing the key role of evolutionary mosaicism in early bird diversification.”13

Summing Up: Oversimplification of Character Traits Leads to “Dino-Bird” Determination

So, with the above “neutral approach” remark in mind, it is essential to recognize specific points.

1. The initially and primary conclusion drawn by the authors in the paper concerns development. As nonreligious researchers, development is the concept that penetrates their method of seeing and translating deep space around them. The information is dealt with based upon evolutionary presumptions, which leads them to conclude that development holds true. That is, they presume development to show development. That is called circular thinking, a kind of sensible misconception. It sounds and appears sensible, however it is not. In completion, they are not showing anything—they are presuming development and creating conclusions that fit their evolutionary worldview.




2. The paper did not discuss any referral of the akinetic skull and its relationship with feeding methods. They just address origins and development. That alone reveals their evolutionary predisposition.




3. The shift of an akinetic skull to a kinetic skull is translated as an outcome of the loss of some bones. However, this concept is countered by other possibilities. “The disappearance of two more structures is attributed by Hofer to the development of the avian type of kinesis, the ectopterygoid and the epipterygoid.” This hypothesis might be real, however there appears to be an alternative description.14 Either method, if the loss of the bones was the reason for this “evolutionary transition,” that still does disappoint any development occurring as there is no boost of info however a loss.




4. An akinetic skull is not a function that is distinct to dinosaurs. The authors of the Cratonavis zhui paper claim that their “study reinforces the latest hypothesis that a true kinetic cranium is absent over a large part of Cretaceous avialan history.”15 In associated work, they recommend that other extinct birds, such as enantiornithines, likewise provided an akinetic skull. While their findings stay open up to other analysis, it is still sensible to develop that this particular (if it really exists in a lot of Cretaceous birds as the authors declare) relates to a function needed for various extinct birds’ lives and has absolutely nothing to do with development. Indeed, there are some modern-day birds that display what is called a pseudoprokinetic skull.16




5. The fossil record provides difficulties—a few of the skulls are not discovered in their totality, some are crushed, and some are simply not discovered at all. Hu et al. state, “Although the fossil record of stem birds and their closest relatives has grown enormously over the past 3 decades, detailed information concerning palatal morphology in these taxa is extremely rare due to their delicate nature and the crushed, 2D preservation of most specimens. With only few exceptions, the palate is partially preserved in 2D…. Consequently, despite great interest, the origin of the modern avian palate and cranial kinesis from the akinetic nonavian theropod condition remains poorly understood.”17 The structure of the taste buds, based upon evolutionary idea, appears to be associated with kinetic motion.18 But the conservation of the taste buds experiences lots of difficulties. Which brings the authors to confess that they cannot comprehend much about it. Despite this absence of understanding, they make lots of claims of the significance of an akinetic skull to the expected relationship in between dinosaurs and birds.




6. 
   Those difficulties provided by the fossil record likewise cause possible mistakes in determining some skull aspects and even translating them in a different way. Wellnhofer provides a few of those examples associated with the skull bones of Archaeopteryx.

   1. Quadrate analyses:
      1. a possible sphenoid piece
      2. bearing a single head, which is a dinosaur function
      3. bearing a double head, which is a bird function

   2. 
      Palatine analyses:

      1. as triradiate, which is a bird function
      2. as tetraradiate, which is a dinosaur function.19

   
   
   So, when handling skull bones, much care requires to be taken. There are lots of possibilities of errors which requires to be considered prior to making claims and analyses.




7. Most of the functions of the expected “non-avian theropods” compared to Cratonavis zhui come from troodontids, oviraptorids, and dromaeosaurids, which have actually likewise been thought about birds by some nonreligious researchers. Feduccia, in his book released in 2020, recommends and offers proof that supports the positioning of troodontids, dromaeosaurs, and oviraptorosaurs as part of the Aves group.20 That is, when the authors compare Cratonavis zhui to those 3 groups, he is comparing bird with bird, not bird with dinosaur.




8. Many qualities Cratonavis zhui presents are the exact same as other birds, consisting of Archaeopteryx, which, in spite of some researchers’ efforts to show the contrary, continues to be thought about a bird.

Conclusion

Judging an animal from one fossil specimen is rather hard, nevertheless the Cratonavis specimen reveals lots of functions of a bird.

Now we take on the huge concern of whether Cratonavis zhui is a bird or a dinosaur (and not some dino-bird mosaic as the evolutionists spin it). Judging an animal from one fossil specimen is rather hard, nevertheless the Cratonavis specimen reveals lots of functions of a bird. Keep in mind that there were no specific plumes or conclusive plume impressions discovered on this fossil (however see previous discuss this). There was no keel on the fossil, and a keel is a rather essential diagnostic particular for flying birds due to the fact that their flight muscles connect there. But that doesn’t dismiss a flightless bird. There are even a couple of other fossil birds which do not have a keel however have other flight muscle accessory websites and might fly (like Archaeopteryx). Also, a keel is a really intriguing animal part that can be quickly lost in a watery environment. Once the muscles and tendons break down, it quickly ends up being disarticulated. Cratonavis has other functions too, like a pygostyle, semilunate metacarpals, and so on., that are really birdlike. Also, the paper points out that they discovered some other functions that might have assisted the flight system, like a lengthened scapula and very first metatarsal.

As kept in mind above in the akinetic skull area, this kind of skull is typically believed to be diagnostic of non-avians, however even that presumption has actually been cast doubt on by evolutionary ornithologists considering that other birds have this function. Much more requires to be understood about the environment and diet plan of Cratonavis prior to that concern can be addressed. The authors of the paper desire this to be a mosaic form, although they confess that its morphology is perplexing (like its having a toothed jaw, whereas its “slightly older ancestors,” the Confuciusornithidae, have no teeth). The authors even discuss the “plasticity” of fossil bird morphology. It has actually an expected mix of primitive and sophisticated characteristics which runs counter to the smooth, direct development from Archaeopteryx to albatross, which is what is constantly worried in the dino-to-bird evolutionary story.