Are birds dinosaurs? What does the evidence tell us?

Written by Randy Ravest.

A large group within the scientific community accepts that all birds are evolved or modified dinosaurs (BADM: Birds are dinosaurs modified), at least from the genetic point of view, likewise, that some or several taxa of dinosaurs possessed some type of plumage. This idea began with the biologist Thomas Henry Huxley when he compared the small dinosaur Compsognathus with a "Chicken", in those years, for naturalists, paleontologists and biologists, birds were not dinosaurs, but according to the taxonomic foundations of Carl Linnaeus, the birds had their own class "Birds". But this position was solidified in 1969 (the year in which man landed on the Moon), when the doctor and paleontologist John Ostrom suggested that the similarities between Archeopteryx (a species with features of a bird and a dinosaur) and his recently discovered Deinonychus, kept a relationship, roughly, by the shape of the skull, the teeth, the S-shaped neck, the wrists, the hips, the hind limbs and a long vertebrate tail, (on the claws among birds and raptors, the tubercles flexors or bony roots are not the same). Along the way, he was joined by other paleontologists, such as his former student, paleontologist Robert Bakker, who in 1975 wrote an article for Scientific American "The Renaissance of the Dinosaurs," exposing their characteristics as active, endothermic (or blood-borne) animals. hot as they said at that time). In 1950, cladistics ("Fundamentals of a theory of phylogenetic systematics", published in Germany) was born, it is a method of analysis, which uses the shared apomorphic characters or synapomorphies of organisms (synapomorphy is a set of characteristics derived and shared by a group of taxa). Cladistic analysis is the basis of most modern biological classification systems that attempt to group organisms and species based on their evolutionary (phylogenetic) relationships... this started as a theory and would become almost a law. The premise of "Birds are dinosaurs" began as a timid assumption and over the years, it became quite a hypothesis within the scientific community and a topic of intense debates that would extend for half a century.

Today, a large group of paleontologists often say openly in the media that "Birds are dinosaurs"... plain, as if it were a fact that does not warrant any justification and almost without stopping to give any rational explanation to the general public who probably do not fully understand this, perhaps hoping that others will accept it as a truism, (sometimes committing, intentionally or not, the Fallacy of Incomplete Evidence or Cherry Picking, "I show you only what I want you to see." see"... and also in the Fallacy of Authority, in other words, that the opinion of a scientist is unquestionable), and that people omit detracting scientific information, because most people, although they do not have a sufficient education science, they are very intelligent and critical, and unlike previous decades, today they are very skilled at using the Internet and searching for scientific articles... and several do not share that premise, for different reasons. reasons, some of them genuinely scientific. Even so, some evolutionary biologists persist in posing this as an intellectual challenge to the common people and very confident that people will not respond with scientific arguments. On the other hand, the rest of the paleontologists refuse to expose themselves to public criticism and avoid the issue. Perhaps many will find it absurd or fanciful to relate birds to dinosaurs, it is natural, birds are very different from common reptiles (including mesotherms) and for this reason, from the beginning, this topic has been object of not a few controversies, laughter, ridicule and jokes, but apparently, evolutionists do not care about criticism and ridicule, others do and since they are aware of this, they tend to evade the issue or when they affirm that birds are dinosaurs, they do it as if it were a commitment, but quietly or quickly so that it goes unnoticed and thus avoid debates.

However, since the 1970s, almost on par with Dr. Ostrom, a sector of the paleontological community, specifically paleornithology and ornithology, the scientific branches dedicated to the study of prehistoric and current birds, disagreed... The greatest proponents of this vision are paleornithologist and Dr. John Alan Feduccia, Stephen Czerkas in part, Dr. John Ruben, paleontologist and physiologist and his former student Dr. Devon Quick of Oregon State University and South African paleontologist and expert in Taphonomy, Theagarten Lingham-Soliar. His scientific vision in this regard, he adopted the title of BAND (Birds are not dinosaurs), some in an effort to ridicule this scientific position, nicknamed him "Bandit" or "Bandida", although it is not a scientific term nor does there exist any meaning of this related word in no dictionary. They postulate that birds arose from a group of highly metabolic archosaurs or lizards during the Triassic and that birds would not be dinosaurs, but would have a common ancestor with dinosaurs and diverged from them since the inception of reptiles. Although there is too much information and we could spend days talking without stopping about all the similarities between dinosaurs and birds, (if we take into account that almost all animals resemble each other, even without being closely related and by Convergent Homoplasies or independently acquired traits ), we will try to focus on key points that could suggest the opposite and we will analyze them one by one, they would seem simple details, however, of a great incidence that may be able to reconsider the theropod origin of birds, it should be noted that these studies so far have not have been refuted.

1. Did dinosaurs breathe in the same way as modern birds?

2. Were they endothermic like birds?

3. Did they have feathers like birds? Did they have the same melanosomes?

4. Protoavis, a bird that lived before the raptors?

 

Let's get down to business:

1. Did dinosaurs breathe in the same way as modern birds?

Birds do not have the same respiratory system as other animals, their lungs have extensions commonly called "air bags or sacs" A true wonder! Thanks to them, the Andean condor can reach 7 kilometers in height in flight and the Cinnamon Tarro duck can fly over the Himalayas. Birds themselves are spectacular and totally out of the ordinary creatures, and surely for that very reason, in 2009 Dr. Devon Quick and Dr. John Ruben published the paper "Cardiopulmonary Anatomy in Theropod Dinosaurs and Its Implications for Extant Archosaurs." In this, Quick and Ruben verified a feature typical of birds and apparently absent in theropod dinosaurs, on the structure of the pelvis and the joint of the femur and knee, they compared the femoral complex of an ostrich and that of a tyrannosaurus. In the case of the ostrich, there is a semi-horizontal femoral complex that, attention "Incorporated into the abdominal wall of the body laterally" and this mechanism would prevent the collapse of the air bags during paradoxical respiration (when the diaphragm moves up in the inhalation and down on the exhalation). On the other hand, in Tiranosaurus, there was no such mechanism to prevent the collapse of the airbags, moreover, both in this taxon and in the other theropod taxa, the distal femur rotated freely when walking and was not incorporated into the abdominal wall. laterally as in birds. In very simple words, birds cannot rotate their knee freely like theropod dinosaurs, much less lift it up to their belly, doing so would cause the airbags to collapse with their knees. Although subsequent articles have been published supporting avian respiration in theropod dinosaurs, on the involvement of the femur and locomotion, we can see that these points have been completely neglected and ignored, therefore we logically conclude that the study by Quick and Ruben has not been successfully refuted. [1] Probably John Ruben was not taken very seriously when he claimed to identify a hepatic piston respiratory system in the fossil of the Compsognathidae Sinosauropteryx, that is the respiratory system of current crocodiles, it is curious that paleontologist Phil Bell demonstrated ISO sensory scales in his relative Juravenator starki, these scales are present in modern crocodiles and are used to detect prey underwater. Would the respiratory system suggested by Ruben be practical for hunting underwater in Compsognathidae?

Ostrich (Struthio) and Tyrannosaurus rex. Note the widely open abdominal lumbar regions in both taxa (asterisks). In the ostrich, the semihorizontal femoral complex is incorporated into the lateral body wall and helps prevent paradoxical ventilatory collapse of the large abdominal air sacs. No such collapse prevention mechanism existed in Tyrannosaurus: during locomotion in theropods, the distal femur rotated freely and the femoral complex was not incorporated into the abdominal wall. (Figures modified from Bolzan, 2001; Figures modified from Osborn, 1916). Credits: DE Quick and JA Ruben.

(AC) Anterior views of the pelvis of Allosaurus fragilis (AMNH 5753). The free pelvic cross-sectional area is highlighted in red (B) and the total pelvic area is highlighted in blue (C). (DF) Posterior views of the pelvis of Melagaris gallopavo (KU 86024). The free pelvic cross-sectional area is highlighted in red (E) and the total pelvic area is highlighted in blue (F). Free pelvic area measurements as a function of total pelvic area were compared between taxonomic groups.

It is possible that someone questions the comparison between a large theropod like Allosaurus and a turkey. But the same thing happens with the other non-avian theropod dinosaurs and raptors of primitive body plans, the cavity of the pelvis is too small and narrow and does not have space for air sacs like birds, whose cavity is very wide:

Struthiomimus.

Velociraptor.

Free pelvic cross-sectional area as a function of total pelvic cross-sectional area in modern birds, primitive birds, and dinosaurs. Modern birds (Neornithes) have a significantly greater pelvic cross-sectional area than all dinosaurs (Dinosauria) measured [P < 0.01, simple linear regression; Neornithes 5 (0.63 6 0.010)x 1 (0.63 6 1.12), r 2 5 0.984; Dinosauria 5 (0.20 6 0.0065)x 1 (9.12 6 9.14), r 2 5 0.969]. Dinosaur pelvic foramina were significantly smaller than those of modern birds, and therefore probably lacked the necessary space capable of supporting the abdominal air sacs the size of modern birds. Early Birds (Birds) 5 (0.71 6 0.0083) 2 (0.97 6 0.529), r 2 5 0.999. l, All Modern Birds (Neornithes) n 5 62, ~, Early Birds (Aves) n 5 9, ^, All Dinosaurs (Dinosauria) n 5 19.

Comparative anatomy visual exercise.

Running ostrich skeleton. Its ribcage is short, but wide. The tarsus, metatarsus (fused) bone is very long and is a trait shared by all birds, likewise the tibia or tibio tarsus... and these contrast with the small femur that extends laterally to the abdominal wall, as Quick and et al. Ruben and pelvic, pubic, and ischium bones fused backwards to provide a large space for organs and air sacs. Birds hardly need to articulate the knee to walk or run, the tibia and tarsus cover the distance they need to cover in one stride. All birds have the shortest femur with respect to the tibia and tarsus, this feature is clearly seen in the first flying raptors dated before Archeopteryx, Xiaotingia zhengi, Aurornis huxleyi and after Archeopteryx, Jinfengopteryx elegans, Microraptor zhaoianus, Zhenyuanlong suni and Sinornithosaurus.

Reconstruction. Gallimimus skeleton. Her name means "chicken impersonator". Its ribcage is very long compared to that of birds, reminiscent of reptiles. Although the tarsus metatarsus is fused, the hip bones, the pubis and ischium, are in the same position as the hips of reptiles or Saurischia... and once again, the pubic cavity indicates that there is no space for air sacs. Also, unlike birds, the femur is not shorter than the tibia.

Skeleton of a chicken. We'll see if it looks like Gallimimus. The tarsus metatarsus is fused (a trait shared by all birds). And the hip bones, the pubis and the ischium are so fused, that the ischium is barely distinguishable. And yes, the femur is shorter than the tibia.

Reconstruction. Archeopteryx skeleton. Two features shared by all birds stand out in the ankle region: a fused metatarsal tarsus bone. And in the pelvis, separate and extended V-shaped bones, which provide a space for air sacs, as in birds and unlike theropod dinosaurs where this space is extremely reduced. Like birds, the femur is shorter than the tibia. Credits: Ryan Carney.

Reconstruction. Deinonychus skeleton. Although it is true that the bones of the pelvis, pubis and ischium, are directed backwards, they are not the same as those of the ostrich or the rest of the birds, they are reminiscent of those of Gallimimus and the reptiles, Saurischia, only with a different orientation . And it should be noted that the proportions of the bones of the hind limb are completely different, the tarsus is not fused. Like Gallimimus, the femur is not shorter than the tibia, therefore it is not like that of birds.

Some will shout at me "Deinonychus has the same hip as Archeopteryx!"... and yes, it's true, they look alike, because they are not the same. But don't forget... Deinonychus doesn't have the trait shared by all birds: the fused tarsus metatarsus. ¿Why is it so important? Because being fused, the distal femur will not rotate freely, but will manage to keep it fixed, so that the entire limb and the knee articulate like in birds, to walk like birds and this movement is compatible with avian breathing and knees. don't collapse the air sacs in your strides, okay? Others will demand "But there are raptors where the tarsus is fused, Microraptor and Zhenyuanlong, just like in birds!" And they are absolutely right, however, there are paleontologists who classify them as birds and these two species are dated 20 million years before Deinonychus, in simple words, there are species very similar to current birds, but millions of years before Deinonychus. raptors of primitive body planes proper.

2. Were they endothermic like birds?

Before and after the 70s, paleontologists seemed harassed with the reptilian image of dinosaurs, they could not conceive of upright and active animals being ectothermic or cold-blooded reptiles as was said at that time, even having Archeopteryx, that is why that Ostrom's observations on Deinonychus hit the community so deeply, some dinosaurs looked a lot like birds, so much so that fantasizing that they were endothermic or warm-blooded seemed very tempting to posit their evolutionary origin of the birds, like a puzzle that was finally somewhat more complete. Despite the lack of conclusive fossil evidence to affirm that dinosaurs were truly endothermic (or warm-blooded) animals, like birds and mammals, many were already accepting it as a fact, due to the upright posture of dinosaurs, where the femur lies under the body unlike reptiles, which did not drag their tails as there was no ichnological evidence or footprints to support it and due to the mere relationship of kinship with birds.

It is here when the work of the biologist Robert A Eagle and his equipment plays a fundamental role. It is interesting that both Eagle and his colleagues have nothing to do with the BAND position or Birds are not dinosaurs. In 2015, this group of specialists so to speak "Took the temperature of dinosaurs", the article entitled "Isotopic order in eggshells reflects body temperature and suggests different thermophysiology in two Cretaceous dinosaurs", is in abstract, an isotopic thermometry examination, they analyzed the minerals in the fossilized eggshells of an Oviraptor, found in the Djadokhta region, Mongolia and also those of some titanosaurs from Argentina. The analysis would determine the body temperature of the mothers during the gestation period, the minerals would indicate that their formation would have been at a lower body temperature than that of the birds.

As they literally said:

"Oviraptorids had slightly cooler temperatures, indicating that they had not developed the body temperature that we see in birds today," Eagle said. Yes, 32ºC, 8 to 10 degrees below birds, because the body temperature of birds is 42 to 40ºC, at that temperature, we being endotherms, we would have a terrible fever and maybe we would die, could a dinosaur survive? to such a fever? Or on the contrary, if we marked 32° on the thermometer, we would be dying of hypothermia. Could a bird live its entire life at a temperature as low as that? Although the hummingbird can reduce it to 15 or 3 degrees, it needs to return to its normal body temperature to survive, 42 or 40 degrees or it could die.

"Oviraptorid eggshells would have produced temperatures lower than most modern endotherms, implying that this taxon did not have comparable thermoregulation to modern birds, but could raise its body temperature above normal. [...] We did not observe strong evidence of end-limb ectothermy or endothermy in the species examined.The body temperatures of these two species indicate that variable thermoregulation probably existed among non-avian dinosaurs and that not all dinosaurs had temperatures body structures in the range seen in modern birds.... Mesothermy in dinosaurs is supported by a recent theoretical study and highlights that the debate over dinosaur thermophysiology is not a matter of a simple dichotomy of "blood hot" versus "cold-blooded".

They also carried out a similar experiment with the teeth of two sauropods and determined that the temperature for the Brachiosaurus would have been 38.2°C and for the Camarasaurus 35.7°C, had they been endothermic, the temperature could have been around 45°C according to Eagle, which which is ruled out, because elephants mark 36°C and the body mass and weight of these dinosaurs was the equivalent of 10 or 30 elephants, like a whale and whales as endotherms, mark a temperature of 93° to 107°C. And for that reason, Eagle and his collaborators concluded a mesothermy for dinosaurs like Oviraptor and a gigantothermy (which is a variant of mesothermy) for sauropods. The mesothermy present in the leatherback turtle, the white shark, the tuna and the opah fish, is a variable thermoregulation system, possible thanks to three factors, an arterial complex called "Rete mirabile", muscular chains and a high index of body fat. , which allows the leatherback to navigate in frigid waters. An incredible feat for a sauropsid or reptile! Don't you think?

3. Did they have feathers like birds? Did they have the same melanosomes?

"Protofeathers", a term born from certain fluff or filaments in some non-avian dinosaur fossil slabs. We have as an example Yutyrannus huali, Beipiaosaurus inexpectus and Sinosauropteryx prima. When John Alan Feduccia declared that Sinosauropteryx feathers were actually type 1 collagen fibers, Feduccia was laughed at and ridiculed by many, but a later discovery in 2003 would prove Mr. Feduccia right... his South African colleague, Theagarten Lingham-Soliar published the paper "Evolution of Birds: Ichthyosaur Integumentary Fibers Adapt to Dromaeosaur Protofeathers." [3] Which showed the fossil of an Ichthyosaurus, a marine reptile, with the same protofeathers or filaments of dinosaurs, remember, this was not a dinosaur. The last case might catch your attention, but it seems true, these filamentous structures were found in the fossil of an Ichthyosaurus. Although in 2017, a group of paleontologists published an article called "On the alleged presence of fossilized collagen fibers in an ichthyosaur and a theropod dinosaur", whose authors are: Fiann M. Smithwick, Gerardo Mayr, Evan T. Saitta, Michael J Benton and Jakob Vinther, where they would refute collagen fibers in Ichthyosaurus, as "Scratches" in the sediment... but that's not all.

Apparent type 1 collagen fibers in Ichthyosaurus fossil, by Teagarthen Lingham-Soliar, (2003), refuted as scratches in sediment in 2017.

What about the dolphin carcass? What did Theagarten Lingham-Soliar discover that could mean so much for paleontology and science? In 2004, Mr Lingham-Soliar carried out an experiment with the carcass of a dolphin that he buried in dry sand (not in seaweed or grass), entitled "The Origin of Dinosaur Feathers: Perspectives from Collagen Fibers". of dolphins (cetaceans)" [4]. In summary, the fat of the decomposing animal formed a kind of "Plumage", which turned out to be type 1 collagen fibers, as predicted by Dr. John Alan Feduccia, that is, bundles of fibers or tissues in the process of decomposition. They were so fine that they did not achieve the thickness of the tubular bristles of Psittacosaurus, which are more reminiscent of the elongated scales of iguanas or the spicules of the bearded dragon... yes, much as many deny it with anger and frustration and although Feduccia has made various mistakes in the past, yes he was right on this occasion, not so those who claimed that Sinosauropteryx was a bird... and this had such an impact on paleontology that even Philip Currie himself, paleontologist and faithful defender of the feathered dinosaurs, he considered that this could have happened with some dinosaurs.

Type 1 collagen fibers in the carcass of the Teagarthen Lingham-Soliar dolphin. (2004).

And to top it off, in 2014, Mr. Lingham-Soliar did it again! While Mr. Godefroit was publishing the feathers of the Siberian ornithischian dinosaur Kulindadromeus, Lingham-Soliar published a commentary in response to his article entitled 《Commentary on “A Jurassic Siberian Ornithischian Dinosaur with Feathers and Scales”》[5] where showed the same phenomenon in a reptile, a basilisk, whose degraded scales formed type 1 collagen fibers.

Collagen fibers in basilisk reptile, Psittacosaurus, Kulindadromeus, Sinosauropteryx and Ostrich, by Lingham-Soliar.

Some people might take a denial stance and argue that filaments in dinosaurs sport the same pigments and melanosomes as bird feathers, inspired by the 2010 article "Fossilized Melanosomes and Color in Cretaceous Dinosaurs and Birds" [ 6]... nobody likes to give bad news, ever, but said eumelanosomes and pheomelanosomes that give the dark and reddish coloration, are the most abundant pigments in nature, they are even present in squids, amphibians and mammals, such as the bat Palaeochiropteryx... and in ourselves, human beings.

Or they probably turn to the Velociraptor ulna fossil, 2007's "Feather Knobs on the Velociraptor Dinosaur" [7] where Turner, Makovicky, and Norell compared a faint six marks on the raptor ulna bone to the bony knobs on the ulna of the vultures, however, in the birds mentioned, are not six timid marks, but ten bumps... and we would be missing four or five marks to have a "Fully Feathered Arm", as the unfortunate Velociraptor is usually represented.

Ulna bones of Velociraptor and vultures compared. (2007).

Perhaps they will seek refuge in the Zhenyuanlong fossil by Junchang Lü and Stephen Brusatte [8], to emphasize that the raptors were completely feathered like birds, well, it goes without saying that Zhenyuanlong did not have six barely distinguishable marks like Turner's Velociraptor, Makovicky and Norell, but more than thirty complex or pennaceous bird-like feather markings... and that both Lü and Brusatte admit that the species sports traits not seen in most Dromaeosauridae (raptors), they used the term "homoplasy" , this is particularly interesting.

Fossilized forearm of Zhenyuanlong, fully feathered with markings of approximately thirty feathers. (2015).

We can all easily verify the following fact: yes, like birds and unlike theropod dinosaurs, Zhenyuanlong's femur is significantly shorter than the tibia, so it walked like a bird and breathed like a... technically Speaking, it could be a basal raptor with highly derived features or outright a bird with Convergent Homoplasies, among them, a ranphotheca or broad toothed beak, like the primitive Archaeornithes or Enantiornithes birds. There is a detail that has not been clearly established with Zhenyuanlong, the structure of its inner ear, which is a decisive feature to determine whether or not it was a theropod dinosaur or whether it was a true bird.

Zhenyuanlong. Credits: Emily Willoughby.

The biological phenomenon of Convergent Homoplasies or analogies [9], are traits acquired between two animals that are not close relatives or that belong to different classes, it is for this reason that many animals resemble each other, as seen in the skeletons of the tuatara and platypus, or the phalanges on the flippers of prehistoric marine reptiles (for example, tylosaurus) and present-day cetaceans (for example, whales), or the flattened snouts of Hadrosaurus, anseriform birds (ducks), and the platypus again... or finally in the hind limbs of theropod dinosaurs, birds and kangaroos ending in three or four fingers. Even this is seen at small scales, in Molecular Homoplasies, in the eyes of squids and mammals, both have ocular nerves, retina, cornea and lens, without being related or in the same class... or at the molecular level, rats and bananas share the protein H84T or better known as "Banana Lectin" or "BanLec", it "reads" the sugars on the outside of viruses and cells and was modified to fight HIV... or in one of those, Did you not know that salmon proteins are absorbed during the bear's digestion and then excreted by the bear, serving as fertilizer for the forest vegetation? Could this be the explanation for the amino acids in Chris Organ's tyrannosaurus protein seen in chickens and other flightless birds? Could it be that Zhenyuanlong was just a bird with convergences or analogies, which developed convergently to the Maniraptora dinosaurs? What about Hoacin and his fingers in the wings? Or the mountains at the hummingbird's peak? Do these traits seen in dinosaurs stop being birds? It is very likely that when we see a Zhenyuanlong in life, we would think that it is a bird, or at least that is what all its artistic representations suggest, because it was clearly not the same or identical to Velociraptor.

Hoacin (Opisthocomus hoatzin).

Next, we will see a series of examples of Convergent Homoplasies or Convergences, even between species of different classes.

Tuatara or sphenodont and platypus skeletons.

Phalanges on the flippers of Tylosaurus and a cetacean (whale).

Hadrosaurus, duck and platypus skulls.

Hind limbs of theropod dinosaur, bird and kangaroo.

Eye of squid and mammal compared.

4. Protoavis, a bird that lived before the raptors? 

And we regret to give bad news to those who believe that birds are dinosaurs, because if the finding of Archeopteryx (155 Ma ago), is anachronistic and much older than most members of the Eumaniraptora clades (137 Ma, with a distance from 18 Ma), Trodontidae (143 Ma, by a difference of 12 million years, if Jinfengopteryx elegans is considered a troodontid dinosaur and not a bird), Dromaeosauridae and Deinonychosauria... and even then it is not enough, there is another more exaggeratedly anachronistic fossil evidence of birds millions of years before the Maniraptora clade (this clade dated 168.3 million years ago, that is, 41.7 million years later), is Sankar Chatterjee's Protoavis texensis of 210 million years ago. years in the late Triassic, yes 55 million years before Archeopteryx. As stated in his article by Chatterjee:

"Pheasant-sized Protoavis [...] bears resemblance to the bird Ornithurae [...] the structure of the otic capsule [...] the generalized pneumatization of the elements of the braincase [...] a full complement of tympanic recesses and the presence of an epiotic [...] teeth are retained at the tip of the jaws, but posterior teeth are lost [...] With a highly specialized central nervous system associated with balance, coordination, muscle control and proprioception [...] Furcula with a hypocleidium, keeled sternum, humerus with a well-developed head, bicipital crest and brachial depression, alar folding mechanism, fusion of ilium and ischium (fused as in extant birds) [...] The presence of feathers is inferred from the protuberances of the quills on the metacarpals".

Protoavis, a dubious genus with a bird's inner ear and features typical of modern birds? [10]...according to some paleontologists, Protoavis is a natural chimera, victim of a disaster that plunged into a quagmire, gathering the bones of various animals...according to Phil Currie and XJ Zhao, it was very similar to Troodon, a dubious genus of theropod dinosaur that lived at the end of the Cretaceous period, 75 million years ago, that is, 135 million years after Protoavis, although they did not classify it as a theropod dinosaur, they limited themselves to affirming that it had avian features seen in other theropods, of course, in those that looked like real birds! Gauthier & Rowe, Dingus & Rowe argued that the hindlimb of Protoavis would belong to a coelophysioid, Coelophysis from 203 Ma, 7 million years later than Protoavis. Finally, in 2001, Marjanovic and David suggested that it would be a depranosaurus, a chameleon-like lizard that lived in the Triassic period, yes, but 200 Ma, 10 million years after Protoavis... will it be necessary to remind him the paleontologists who deny Protoavis as a bird and propose other species instead, who at least agree with the dates that do not add up at least? It is true that a chimera brings together several fossilized bones, but will it be so difficult to notice that the mineral composition of a fossil is not the same as that of another found millions of years later to know that it is not the same species?

Be that as it may, once again, in the case of being a Depranosaurus, that would be more closely within the BAND view of Feduccia and Wild from 1993, rather than with the theropod origin of birds, since the BAND position posits that the birds originated from a group of archosaurs and not directly from dinosaurs... however, if neither of the two visions, neither BADM nor BAND, is correct, a third position will be necessary "BAOC: birds are another class", as Carl Linnaeus put it at the beginning.

Could the origin of birds be earlier than that of raptors? How else would you explain a flightless enantiornithes bird like Kiririavis mater being found in Brazil, the southern hemisphere, 108 million years ago in the lower Cretaceous? Aren't birds supposed to originate from the northern hemisphere, from the Eurasian region? How did their possible ancestors from the northern to the southern hemisphere cross over? Through a land channel between the two hemispheres? When were these hemispheres joined? In the Triassic and they separated in the Jurassic? Does this again suggest that the origin of birds could be much older? Someone claimed that Protoavis could not be a bird, because the birds were of Eurasian origin and had not crossed into North America until the beginning of the Cretaceous, which does not explain the Kiririavis in Brazil, because the northern and southern hemispheres were already separated ... but if the birds had emerged in the Triassic, when the continents were united in Pangea, this hypothesis would be ruled out and everything would make more sense and logic and the phylogenetic tree of birds would be more orderly.

Although let's be honest, when it comes to classifying a species, the biologist's philosophical orientation greatly influences when interpreting the evidence, for that reason, Protoavis had so many interpretations, because for a militant atheist biologist, Protoavis will always be anything but a bird, while for a more flexible atheist biologist, it could be a bird with highly derived features and on the other hand, a deist biologist could classify it as a bird with convergent features. Otherwise, we will continue repeating over and over again like automata, that Protoavis, Xiaotingia, Aurornis, Anchiornis, Archeopteryx, Jinfengoptery, Wellnhonferia and company, were the rebellious dinosaurs of the neighborhood, species so incredibly basal that they looked like real birds, some feathered boys and with wings, who cry out to enter the party of birds with convergences, but the atheist paleontologists do not let them enter because they do not bring an identity card... victims of a disorder nicknamed "The follies of divergences and anachronies"... or basal species, that is to say, that it occurs to them to appear in the most inopportune places and times... and they would be joined in the dance by another pair of rebels from the neighborhood, Microraptor and Zhenyuanlong who emerged 125 Ma ago, that is, 20 million years before Deinonychus and 50 million years before Velociraptor, another divergence madness? Perhaps for some that argumentative shortcut of the divergence seems more logical, beautiful and even fun or "Chori" as we say in Chile... instead of prehistoric birds that developed convergently to the dinosaurs, for some, not for all, because fortunately there are still people who cling to their sanity and take things more seriously and don't fall for that fallacious shortcut of militant atheism...because let's face it, militant atheists, like young earth creationists, never They have sought the truth, but rather the way to justify and defend their ideology, although the former have caused more damage to Science and Paleontology than the latter. Why? Easy, when you see a militant atheist paleontologist on Twitter smearing his atheist or agnostic colleague, calling him a "Creationist" for the mere fact of disagreeing with the theropod origin of birds, other users perceive a disastrous and unethical work environment, with apparent professionals engaging in criminal behavior, naturally aspiring paleontologists do not want to confront these fanatics and give up studying Paleontology and its associated careers, States notice a low enrollment rate in these careers and do not allocate funds to them... and we are done with paleontologists begging for research funds, do you realize the economic crisis that militant atheists have caused in their fanaticism? The question arises: why do militant atheists call paleontologists who disagree about the theropod origin of birds creationists? Probably, because they know that according to the Genesis of the Bible, chapter 1 verse 21, birds would be among the first terrestrial animals, perhaps for this reason the militant atheist paleontologists and biologists were so terrified in front of the Protoavis fossil in the Triassic and raised a series of absurd and illogical proposals to discredit the fossil... but that's not all, the optimal environmental conditions for the existence of birds already existed in the Permian period. How so? Well, already in the Guadalupian, Middle Permian, there was an abundance of insects and seeds of cycads and conifers, which are the main diet of a bird.

By general culture, we all know that if an animal sports feathers and flies, it is a bird, no matter the shape of its head, neck, wings, tail or legs, it will still be a bird, especially if its inner ear is that of a bird, as raised by Sankar Chatterjee with Protoavis. Likewise, a hominid that speaks, cooks, makes fire, tools and barters, is a human, not an ape and to top it off, the Neanderthal's inner ear scan showed that it was similar to ours, therefore, that it produced words like us. Could it be that Protoavis communicated in a similar way to birds? This is deduced following the principle of parsimony or methodological and philosophical of the friar William of Ockham, in which scientists agree: the simplest explanation is usually the most accurate. As a phenomenon of axiomatic nature, Axiomatic is something evident, unquestionable, indisputable, undeniable, irrefutable, irrefutable, sure, proven, clear, it is something relative to axioms, which is not false or doubtful. Example of use: There are many axioms in mathematics, for example, the result of 2 plus 4 is equal to 4 plus 2.

Yes, the problem with feathered dinosaurs is like that of hominids...it was believed that they were hybridizations or in-between phases...and after finding out that Neanderthal had an inner ear like us, that he wasn't some dumb caveman who communicated to point of growls, but could produce words like us, that Neanderthal and Homo sapiens interbred to give rise to the Preneanderthal lineage in the Middle East and not in Europe, that contrary to hybrids, we are the most adaptable and successful species of all, science leaned towards the idea that hominids were Homo sapiens of different lineages (the term "races" is no longer used, but you get the idea). Yes, ladies and gentlemen, there is still hope, a thread of light for Paleontology, the science that seeks the truth in the past.

Reconstruction Skeleton of Troodon, Late Cretaceous, 75 Ma. Credits: Scott Hartman, 2013.

Protoavis texensis, Triásico, 210 Ma. Sankar Chatterjee. (1999).

Depranosaurs, Triassic, 200 Ma. It is very easy to see the similarities between Troodontids, Depranosaurs and Protoavis, they are as equal as two peas in a pod and they may have lived almost at the same time... or maybe not?

We must remember that dinosaurs are a group of animals belonging to the Sauropsida class and the Diapsida subclass, that is, animals very similar to what Linnaeus classified as reptiles, today we know that not all commonly called reptiles are ectotherms (cold-blooded). , there are some homeotherms such as the overo lizard and mesotherms such as the leatherback turtle. Will there be any feathered reptile today? Any crocodile, alligator, iguana, monitor lizard or feathered turtle? Or a mesothermal one like the Feathered Eagle oviraptor? Or just plain a mesothermal bird with a temperature of 32°? It seems like a rhetorical question, since the answer is so absurdly obvious that we would be embarrassed to answer it... but it is a resounding no... and no, the elongated scales on the diapsid Longisquama were not feathers, since those elongated scales were not they reflect the same pattern as the feathers and were not calluses but bony roots attached to the vertebrae and are clearly seen today in other archosaurs, such as the basilisk iguana. 

And this reminds us of the old scientific statement:

"The [evolutionary] origin of birds is largely a matter of deduction. There is no fossil evidence for the stages through which the remarkable change from reptile to bird was achieved." WE Swinton, "The Origin of Birds", Comparative Biology and Physiology of Birds, A J Marshall ed. (New York: Academic Press, 1960), vol. 1, Chapter 1, p. 1. 

It is probable that now, some feel that they have been cheated or lied to for a long time, but it is not necessary to fall into an Ad Hominem and point the finger and look for liars or charlatans... it happens that paleontology itself has as one of various engines, the search for fossils to verify Darwinian macroevolution or gradualism, transitional fossils (before they were called "Missing Links"), with the aim of completing "Darwin's Tree of Life" or "The common ancestor of all species", as if it were a true puzzle, despite the fact that the Darwinian model is rejected by well-known figures within the scientific community, as New Scientist magazine confirmed:

"A growing number of scientists, and more particularly a number A growing number of evolutionists ... present the argument that Darwinian evolutionary theory is by no means a genuinely scientific theory ... Many of the critics have the highest beliefs intellectual potentials" (June 25, 1981, p. 828). 

A curious fact that may not be relevant is that Charles Darwin and Alfred Wallace were Christians or deists and attributed Natural Selection to a divine act and at the same time, they were against creationism (or the idea of the young earth), because It is assumed that we have advanced as a society and by general culture we know that a Christian who does not believe in macroevolution is not necessarily a creationist, because he accepts the millions of years of the earth, as occurs with various scientists and deists... the irony of this, is that some militant atheists use Darwin and Wallace as referents, as well as Carl Sagan who was not an atheist but an agnostic, that is, he neither rejects nor accepts the existence of God, although his novel "Contact" left the door open. open to an encrypted PI number, hidden by a Higher Being, according to Ellie Arroway.

"The observed patterns and rates of large-scale evolution are not comparable to those hypothesized by Darwin on the basis of extrapolation from modern populations and species. [...] What we find in the fossil record is the opposite of Darwinian gradualism. [...] Populations and species are clearly distinct in all taxonomic groups." Robert Lynn Carroll, paleontologist, University of Michigan and Harvard. 

Source: Carroll, RL. "Towards a new evolutionary synthesis". Trends Eco. Evol. 15, 27-32.

"The tree of life is being quietly buried, we all know that. More difficult to accept is the fact that our fundamental view of biology has to change completely." Michael Rose, evolutionary biologist. Professor in the Department of Ecology and Evolutionary Biology at the University of California, Irvine.

Source: Lawton, Graham: "Uprooting Darwin's Tree", New Scientist (24.1.2009), p. 3. 4. 

Evolutionary biologists like to look for evolutionary homologies or relationships between species, find sibling of, cousin of, close or distant relative of, etc. Taxonomy is an ancient classification system, like cladistics that seeks to express phylogeny or phylogenetics in cladograms, which for us would be like family trees, but evolutionary... a few paleontologists, in particular some evolutionary biologists, take bracketing phylogenetic, in the field of biological evolution as if it were an irrefutable law (when in reality it is just a guide), almost on the same level as the law of gravity, as if it were a sacred book... and those who don't they assume it as sacred that it is, they should be branded as profane, ignorant or "infidels", as if they were desecrating a sacred book, this reflects a clear proselytizing and fanatical position (which seeks followers, in this case, in favor of militant atheism and *theophobia), within modern evolutionary biology. It is likely that they are used to omitting this minor detail, but no less important, when the Swedish naturalist Carl Linnaeus founded Taxonomy or the classification system of species in 1735, he grouped certain species into the same class, however, he was fixist and at that time it was not assumed that two species within the same class had a common ancestor, but that they had similar body plans without being close relatives, exactly that is almost the same as what we now call in biology "Convergent Homoplasy"... interesting right?

If we approach this from critical thinking and scientific reasoning, we could make a simple analogy: What has more weight? The evidence or the interpretation that is made of the evidence? Obviously it is the evidence, because although many interpretations of the evidence are given, it is not perfectible, it must remain immutable and intact. Well, the fossil record is the evidence and phylogenetic bracketing is a method of interpretation for the fossil record, therefore, phylogenetic bracketing must remain at the service of the fossil record and depend on the evidence that it provides and not the other way around, being able to keep fallacies at bay.

On the other hand, fortunately, most biologists and paleontologists disagree with this proselytizing vision and only use cladistics and phylogenetics as a guide to classify new species and are clear that they are perfectible, because at any time, a new fossil discovery just around the corner may leave the current classification out of date and rethink it entirely. Exactly that happened with Chilesaurus diegosuarezi, the dinosaur that amazes paleontologists for displaying traits of both Saurischia and Ornitischia, the two main orders that divide dinosaurs, and this restatement, is considered literally "Pretty" by many paleontologists, because it means a great advance... one so significant, that it involved reorganizing the theropods into Ornitischia and relegating the Herrerasauridae to Saurischia, along with the Sauropodomorpha.

Darwinian gradualist evolution or macroevolution, (which postulates possible transitional fossils from one class to another, descendants of a common ancestor), usually generates much controversy and arouses much media attention and coverage, some paleontologists in turn, they use it to obtain recognition, sponsorship and financial support from a state body and museums... however, this does not mean that Darwinian gradualism is the correct path to clarify the origin of species or to forge the future of paleontology... the real hope of paleontology lies in rediscovering the origin of species from a different prism, not from a common ancestor, but a community of ancestors and reclassifying all phyla, classes, orders, suborders, genera and species. Because let's face it, "Ad ignorantiam" or the "False call to ignorance" is the typical philosophical resource that supports Macroevolution, it means that "The absence of something does not imply its non-existence", exemplifying it, its defenders argue "The absence of evidence supporting macroevolution in the fossil record does not imply that it did not occur" is a purely fallacious argument and has been for almost 163 years, from 1859 to the present day.

"It appears that life had multiple origins. The base of the universal tree of life did not consist of a single root." [...] "The traditional version of the common ancestry theory does not seem to apply to the kingdoms as recognized today; it probably does not apply to many, if any, of the phyla either, and possibly not to many of the phyla either." classes within phyla". (Malcolm Stephen Gordon, professor of biology, University of California, Los Angeles, United States). 

Source: Gordon, Malcolm S.: "The Concept of Monophyly: A Speculative Essay", in Biology and Philosophy, 1999, p. 335. "The Concept of Monophily: A Speculative Essay, Biology, and Philosophy." 

*Theophobia: A) Irrational and sick fear of the gods and religion. (Theophobia - Wiktionary, the free dictionary). B) Theophobia is a neologism to refer to the feeling of aversion to God and the principles of religion. It manifests itself as an absolute rejection of some values preached by various religions, such as moral issues such as abortion, homosexuality, euthanasia and divorce; as well as in religious questions such as the creation of the world and God's intervention in history, his designs for humanity and man's responsibility before the creator. It can be recognized in some of the adherents of militant atheism. (Definition and synonyms of theophobia in the Portuguese dictionary - Educalingo).

References: 

[1] "Cardio Pulmonary Anatomy in Theropod Dinosaurs Implications From Exant Archosaurs", Journal of Morphology, 2009. DE Quick and JA Ruben, (Research Gate, 2009).

https://www.researchgate.net/publication/24443361_Cardio-Pulmonary_Anatomy_in_Theropod_Dinosaurs_Implications_From_Extant_Archosaurs 

[2] "Isotopic ordering in eggshells reflects body temperatures and suggests differing thermophysiology in two Cretaceous dinosaurs". 2015. 

Robert A. Eagle, Marcus Enriquez, Gerald Grellet-Tinner, Alberto Pérez-Huerta, David Hu, Thomas Tütken, Shaena Montanari, Sean J. Loyd, Pedro Ramirez, Aradhna K. Tripati, Matthew J. Kohn, Thure E. Cerling, Luis M. Chiappe & John M. Eiler.

https://www.nature.com/articles/ncomms9296 [3] "Evolution of birds: Ichthyosaur integumental fibers conform to dromaeosaur protofeathers". October 2003. The Science of Nature. Theagarten Lingham-Soliar. Nelson Mandela University.

https://www.researchgate.net/publication/9084195_Evolution_of_birds_Ichthyosaur_integumental_fibers_conform_to_dromaeosaur_protofeathers 

[4] "The dinosaurian origin of feathers: Perspectives from dolphin (Cetacea) collagen fibers".

January 2004. The Science of Nature 90. Theagarten Lingham-Soliar. Nelson Mandela University.

https://www.researchgate.net/figure/Fine-fibers-from-the-SDS-subdermal-connective-tissue-sheath-of-the-decomposing-dolphin_fig2_8958184

[5] Comment on “A Jurassic ornithischian dinosaur from Siberia with both feathers and scales”. October 24, 2014. SCIENCE. Vol 346, Issue 6208, p. 434. DOI: 10.1126/science.1259983. Author: Teagarthen Lingham-Soliar.

[6] "Fossilized melanosomes and the color of Cretaceous dinosaurs and birds". February 2010. Nature 463 (7284): 1075-8. Authors: Fucheng Zhang, Chinese Academy of Sciences. Stuart L Kearns, Patrick J Orr, Michael J Benton, University of Bristol.

https://www.researchgate.net/publication/41166443_Fossilized_melanosomes_and_the_colour_of_Cretaceous_dinosaurs_and_birds#pf13

[7] "Feather Quill Knobs in the Dinosaur Velociraptor". October 2007. Science 317 (5845): 1721. Authors: Alan H Turner, Stony Brook University. Peter J Makovicky, Field Museum of Natural History. Mark A Norell, American Museum of Natural History.

https://www.researchgate.net/publication/5958393_Feather_Quill_Knobs_in_the_Dinosaur_Velociraptor

 

[8] "A large, short-armed, winged dromaeosaurid (Dinosauria: Theropoda) from the Early Cretaceous of China and its implications for feather evolution". 

July 2015. Scientific Reports 5 (1): 1177. Authors: Junchang Lü, Stephen L Brusatte, The University of Edinburgh.

https://www.researchgate.net/publication/281822619_A_large_short-armed_winged_dromaeosaurid_Dinosauria_Theropoda_from_the_Early_Cretaceous_of_China_and_its_implications_for_feather_evolution 

[9] "Can systems biology help to separate evolutionary analogies (convergent homoplasies) from homologies?". 

January 2015. Progress in Biophysics and Molecular Biology 117 (1). Authors: Malcolm Stephen Gordon, University of California, Los Angeles, Julia C Notar.

https://www.researchgate.net/publication/271535568_Can_systems_biology_help_to_separate_evolutionary_analogies_convergent_homoplasies_from_homologies 

[10] "Protoavis and the early evolution of birds". 

January 1999. Author: Sankar Chatterjee, Texas Tech University. https://www.researchgate.net/publication/285958392_Protoavis_and_the_early_evolution_of_birds