Is the pope's headgear adopted directly from a Mesopotamian hat, symbol of worshipping Dagon, as seen in his fish mouth looking mitre?

Question

The Roman bishop of the Catholic church is often wearing a mitre. Countless sites, 'that really know the hidden truth and tell it', make the connection of 'fish mouth' and 'Dagon priest', claiming that the hat has a direct, long and unbroken tradition, like:

The Truth about the Pope’s Hat: fish god(Dagon)
Dagon, Cybele and Catholicism.

The Mitre Hat
The priests of Dagon were known by their “Mitre Hat” which resembled an open mouth of a fish. The same exact hat wore even today by The Pope as well as Cardinals and Bishops. All “priests of Dagon” and the religion that surrounds them, even to this day, is identical to that born in Babylon.
_{–– From Dagon to The Dragon The “Spirit” behind Christianity}

And

The Mitre hat that is worn by Catholic priests, cardinals and the Pope, represents Dagon the Babylonian fish god. The ancient Babylonians worshiped Dagan, the god of agriculture, plenty (food) and good fortune.

The Babylonian priests wore a headdress that represented the worship of Cybele and Dagon. It featured an open-fish mouth on the head, with the rest of the fish body forming a cloak.

In the Roman Empire, it was worn by the head priest of Cybele (the Magna Mater) or the Great Queen Mother Goddess.

Today the Catholic Cardinals, Bishops and the Pope all wear the open fish-mouth mitre, which represents the worship of Cybele and Dagon.

The Mitre hat of Dagan is always worn over the Kippa of Ashtoreth/Cybele, as you can see in the picture of Pope Francis I.
_{–– Roman Catholic Beliefs: Who Is The Roman Catholic Church Really Worshiping?}

One of, if not the, oldest theory was formulated by Alexander Hislop in "Two Babylons":

As the Pope bears the key of Janus, so he wears the mitre of Dagon. The excavations of Nineveh have put this beyond all possibility of doubt. The Papal mitre is entirely different from the mitre of Aaron and the Jewish high priests.
That mitre was a turban. The two-horned mitre, which the Pope wears, when he sits on the high altar at Rome and receives the adoration of the Cardinals, is the very mitre worn by Dagon, the fish-god of the Philistines and Babylonians. There were two ways in which Dagon was anciently represented. The one was when he was depicted as half-man, half-fish; the upper part being entirely human, the under part ending in the tail of a fish. The other was, when, to use the words of Layard, "the head of the fish formed a mitre above that of the man, while its scaly, fan-like tail fell as a cloak behind, leaving the human limbs and feet exposed. Of Dagon in this form Layard gives a representation in his last work, which is here represented to the reader (Fig. 48); and no one who examines his mitre, and compares it with the Pope's, as given in Elliot's Horoe, can doubt for a moment that from that, and no other source, has the pontifical mitre been derived. The gaping jaws of the fish surmounting the head of the man at Nineveh are the unmistakable counterpart of the horns of the Pope's mitre at Rome.
_{–– Alexander Hislop: "The Two Babylons; Or, The Papal Worship Proved to be The Worship of Nimrod and his Wife", Partridge & Co: London ⁷1871 (1853).}

The claim of interest for Skeptics is not about any belief that might build on the alleged symbolism. The basic claim to be analysed is solely to focus on the assertion that 'the bishop mitre was directly adopted from Babylonian priests and their head coverings'. That is a verifiable or falsifiable materialist angle.

This claim is widespread and influential. It rests in most presentations of this claim mainly on two pictorial 'evidences' of antiquity and a resemblance to modern bishop's mitres.

And if not always claimed directly, it at least always assumes and sometimes directly states that there is an unbroken tradition – rooted in the direct adoption of pagan beliefs and symbolism - of clerical headgear.

This is quite a colourful explanation. But is it true? What are the origins of and influences on the pope's headgear?
More specifically: Was it adopted by the Christian church from Mesopotamian headgear that the priests of Dagon wore?

Answer 1

Actually the most distinctive papal headgear, the one that popes used to be drawn wearing in political cartoons to distinguish them from ordinary bishops, is what is called the papal tiara, a tall conical shape with three crowns around it, one above the other. Of course the popes have rarely wore the papal tiara in the last fifty years or so, so younger people might not be familiar with it.

https://en.wikipedia.org/wiki/Papal_tiara

https://churchpop.com/2015/08/12/when-popes-wore-crowns-a-pictorial-history-of-the-papal-tiara/

The bishop's miters or mitres worn by Roman Catholic bishops (and by bishops of some Protestant denominations) mostly in religious ceremonies, were originally conical cloth hats, I believe. Over the centuries miters or mitres became taller and split into left and right parts and then the design was turned 90 degrees and they were worn split into front and back parts. The miters or mitres of eastern Orthodox bishops developed a different form.

https://en.wikipedia.org/wiki/Mitre

The wearing of mitres apparently began about the year 950, in Rome, far from Syria, and early mitres looked much less like fish hats of Dagon priests than modern mitres do.

From the seventeenth century much has been written concerning the length of time the mitre has been worn. According to one opinion its use extends back into the age of the Apostles; according to another, at least as far back as the eighth or ninth century while a further view holds that it did not appear until the beginning of the second millennium, but that before this there was an episcopal ornament for the head, in form like a wreath or crown. In opposition to these and similar opinions, which cannot all be discussed here, it is, however, to be held as certain that an episcopal ornament for the head in the shape of a fillet never existed in Western Europe, that the mitre was first used at Rome about the middle of the tenth century, and outside of Rome about the year 1000. Exhaustive proof for this is given in the work (mentioned in bibliography below), "Die liturgische Gewandung im Occident und Orient" (pp. 431-48), where all that has been brought forward to prove the high antiquity of the mitre is exhaustively discussed and refuted. The mitre is depicted for the first time in two miniatures of the beginning of the eleventh century; the one is in a baptismal register, the other in Exultet-roll of the cathedral at Bari, Italy. The first written mention of it is found in a Bull of Leo IX of the year 1049. In this the pope, who had formerly been Bishop of Toul, France, confirmed the primacy of the Church of Trier to Bishop Eberhard of Trier, his former metropolitan who had accompanied him to Rome. As a sign of this primacy, Leo granted Bishop Eberhard the Roman mitre, in order that he might use it according to the Roman custom in performing the offices of the church. By about 1100-50 the custom of wearing the mitre was general among bishops.

The first example of a mitre of the modern shape appears about 1150.

https://www.newadvent.org/cathen/10404a.htm

The worshp of Dagon, along with all other pagan religions, was discourageed and later forbidden by many decrees of different emperors in the 4th century and later centuries. Paganism became a minority religion practiced in private in about the 5th century BC in most parts of the Roman Empire. I would expect that the last fish hat was publicly worn by some priest of Dagon sometime in the 5th century.

So the present vague resemblance between western bishops' miters or mitres and the fish hats of Dagon priests is relatively new. It is certainly not the case that early Christian bishops were depicted wearing modern miters or mitres or anything else resembling fish hats like they would have been depicted if they were priests of Dagon.

I sort of suspect that the originator of the theory you mentioned was just making up a goofy story to see if anyone would believe it, though the persons who repeat it at the present may sincerely believe it.

Dagon was worshipped for a few millennia by ancient Middle eastern people, mostly in Syria. After the Roman Empire converted to Christanity in the 4th century all pagan reliigons including worship of Dagon were discouraged, and later prohibited, and later persecuted.

When Christianity was forming Dagon waorship was common in a relatively small region of the Roman empire, mostly parts of Syria, while worshp of the Graco-Roman gods was spread over all of the Roman Empire and was the official religion of the army and government and all the upper class members of society. There were also larges numbers of early Christians in the Parthan and later Sassanian Empire, where Zoroastrianism was the state religion and other religions, including Christianity, were sometimes persecuted.

So if the ancient Christians were going to imitate various aspects of non Christian reliigons, they would mostly copy Judiaism, which Christianity ws an offshoot of, and they would secondly copy the two high prestige religions in the lands where they lived, Graeco-Roman polytheism and Zoroastrian monotheism. A comparativley local cult like Dagon worship would probably be way down on their list of religions to copy from.