Saying that it was "prohibited by the Fathers" suggests that they are referring to a previous, ancient council. You are saying they are only referring to Trent itself?
I see what you're saying now. Good question. I'm not sure who or what council Pope Paul III is referencing here with this quote. Sounds like it must be before Trent, one of the earlier councils they had perhaps. Here's a general list of them, and a link that may be helpful in researching it.
Ecumenical Councils
General Information
Twenty-one official Ecumenical Councils have been held. They are listed and briefly described as follows, with the inclusion of some additional Synods and Councils that have historical importance:
Council at Jerusalem (not counted in the 21 Councils) 48 AD - According to the Acts of the Apostles, the disciples of Jesus Christ called a council at Jerusalem to discuss stresses between two parties. One party, led by St. Peter and St. James (the "Lord's brother"), an early leader in Jerusalem, stressed continuity between ancient Judaism and its law and the community that had gathered around Christ. The other, led by St. Paul, stressed the mission of Christians to the whole inhabited world, with its preponderance of Gentiles (or non-Jews). At the council the latter group tended to prevail.
First Council at Nicaea (#1) 325 AD - The First Council of Nicaea (began on either May 20 or June 19, 325 and met until about Aug. 25, 325), the first ecumenical council, devoted itself to the problem of the Trinity, in an attempt to settle the controversy raised by Arianism over the nature of the Trinity. It was the decision of the council, formalized in the Nicene Creed, that God the Father and God the Son were consubstantial and coeternal and that the Arian belief in a Christ created by and thus inferior to the Father was heretical. Arius himself was excommunicated and banished. The council was also important for its disciplinary decisions concerning the status and jurisdiction of the clergy in the early church and for establishing the date on which Easter is celebrated.
First Council at Constantinople (#2) May to July, 381 AD
Constantinople I was called primarily to confront Arianism, the heresy that had been subdued only temporarily by the First Council of Nicaea. It reaffirmed the doctrines of the Nicene Creed and to depose Maximus, the Arian patriarch of Constantinople. They also condemned Apollinarianism, a position that denied the full humanity of Christ. The council defined the position of the Holy Spirit within the Trinity; it described the Holy Spirit as proceeding from God the Father, coequal and consubstantial with him. It also confirmed the position of the patriarch of Constantinople as second in dignity only to the bishop of Rome.
Council of Ephesus (#3) June 22 to July 17, 431 AD - The Council of Ephesus was significant for its dogmatic decrees on the position of the Virgin Mary in the celestial hierarchy and on the nature of the incarnation of Jesus Christ. It was convened in order to respond to the teachings of Nestorius that Mary be considered only the "mother of Christ" and not the "mother of God" (see Nestorianism). After lengthy debates the council reached an accord in which the appellation "mother of God," formally decreed by the council, was accepted by all. The council also refined the dogma on the human and divine aspects of Jesus, now declared to be of two separate natures though perfectly united in Christ.
Robber Synod (not counted) 449 AD - In 449 another council, known in history as the latrocinium, or Robber Synod, met in Ephesus. It approved the doctrines of Eutyches, which were subsequently condemned at the Council of Chalcedon.
Council of Chalcedon (#4) Oct. 8 to Nov. 1, 451 AD - The Council of Chalcedon (451), which defined how the divine and the human elements related in Jesus ("unconfusedly, unchangeably, indivisibly, inseparably"), used some terms that are unfamiliar to contemporary ears. It also condemned the Robber Synod.
Council of Orange (not counted) 529 AD - Augustine had insisted that humans require the help of God's Grace to do good and that this grace is a free gift, given by God without regard to human merit. Thus God alone determines who will receive the grace that alone assures salvation. In this sense God predestines some to salvation. Augustine's teaching was generally upheld by the church, but the further idea that some are predestined to condemnation was explicitly rejected at the Council of Orange.
Second Council at Constantinople (#5) May 5 to June 2, 553 AD - Constantinople II was convoked to condemn the Nestorian writings called the "Three Chapters." Under the virtual tutelage of the emperor, the council proscribed Nestorianism and reconfirmed the doctrine that Christ's two natures, one human and one divine, are perfectly united in one person. Pope Vigilius at first defended the Three Chapters, but later accepted the council's ruling.
Third Council of Toledo (not counted) 589 AD - This Council developed the additional phrase to the Nicene Creed that resulted in the Filioque Controversy and eventually in the Great Schism that divided Christianity into Roman Catholic and Orthodox.
Third Council at Constantinople (#6) Nov. 7, 680 to Sept. 16,681 AD - Constantinople III condemned Monothelitism and affirmed that Christ has two wills, one human and one divine, but that these are without division or confusion. In addition, it condemned an earlier pope, Honorius I, for supporting that heresy. This Council is also called Trullanum.
'Robber' Council of Constantinople (Orthodox) 754
Second Council of Nicaea (#7) 787 AD - This Council ruled on the use of saints' images and icons in religious devotion, declaring that whereas the veneration of images was legitimate and the intercession of saints efficacious, the veneration of icons must be carefully distinguished from the worship due God alone.
Note: The above seven great councils are regarded as ecumenical by both the Roman Catholic and Orthodox Churches. The Orthodox Church even identifies itself as the 'Church of the Seven Councils'.
Photius (not counted by either Catholic or Orthodox) 867 AD - In 867, Photius summoned a council that deposed Pope Nicholas. The conflict, purely administrative at the beginning, had acquired doctrinal undertones when Frankish missionaries in Bulgaria, acting as Pope Nicholas' emissaries, began to introduce an interpolated text of the Nicene Creed. In the original text the Holy Spirit was said to have proceeded "from the Father," whereas in Carolingian Europe (but not yet in Rome) the text had been revised to say "from the Father and the Son" (filioque). This began the division that eventually split the Catholic and Orthodox Churches apart two hundred years later in the Great Schism.
Fourth Council at Constantinople (#8) Oct. 5, 869 to Feb. 28, 870 AD - Constantinople IV made no new dogmatic decisions; instead, it greatly contributed to the growing split between the Eastern and Western churches. The principal action was to depose Photius, the patriarch of Constantinople, for usurping his ecclesiastical position. This Council was only first called Ecumenical about two hundred years afterwards. Later, Photius was restored to his see, and he held another council in 879-80. That later council, not that of 869, is considered ecumenical by the Orthodox church.
Photius (not counted by Catholic, but #8 by Orthodox) Nov. 879 to Mar. 13, 880 AD - In 879-80 a great council, presided over by Photius, confirmed the original form of the Nicene creed, and normal relations between Rome and Constantinople were restored. The Orthodox Church called this the Council of Union.
Council of Clermont 1095
Pope Urban II preached for and launched the First Crusade.
First Lateran Council (#9) Mar. 18 to Apr. 6, 1123 - The First Lateran Council was called to ratify the Concordat of Worms (1122), which formally ended the lengthy Investiture controversy.
Second Lateran Council (#10) April, 1139 - The Second Lateran Council was convoked to reaffirm the unity of the church after the schism (1130-38) of the antipope Anacletus II (d. 1138). It also condemned the teachings of Arnold of Brescia.
Third Lateran Council (#11) Mar. 5 to 19, 1179 - The Third Lateran Council ended the schism (1159-77) of the antipope Callistus III and his predecessors. It also limited papal electors to members of the College of Cardinals.
Fourth Lateran Council (#12) Nov. 11 to 30, 1215 - This council sanctioned a definition of the Eucharist in which the word transubstantiation was used officially for the first time. The council also attempted to organize a new crusade to the Holy Land and to encourage crusading efforts against the Albigenses and Waldenses. Many precepts still binding on Roman Catholics (such as the Easter duty, or obligation, of annual confession and Holy Communion) were adopted at this council.
First Council of Lyons (#13) June 28 to July 17, 1245 - Confirmed the deposition of the Holy Roman Emperor Frederick II.
Second Council of Lyons (#14) May 7 to July 17, 1274 - A new crusade was organized, and regulations regarding the papal election were approved. An effort at reconciling the Catholic and Orthodox Churches failed.
Council of Vienne (#15) Oct. 16, 1311 to May 6, 1312 - Abolished the Order of Templars, and passed some Church reforms.
Council in the Orthodox Church 1341 - Doctrinal definition of Grace.
Council in the Orthodox Church 1351 - Doctrinal definition of Grace.
Council of Constance (#16) Nov 5, 1414 to Apr. 22, 1418 - Throughout the Middle Ages, even Western or Roman Catholics themselves debated the convoking and authority of councils. Although all the bishops and theologians agreed that the pope should have special prerogatives, for several centuries reformers claimed that when protesters had grievances, they could appeal from the pope to a council. Out of these reformist parties came a theory of Conciliarism, the idea that a council is ultimately above the pope. The Great Schism in 1378 brought this debate to a head, since there were then two and later three popes. The Council of Constance (1414-18) settled the division.
Council of Basel (#17a) July, 1431 to May 4, 1437 - Established that the Council had higher authority than the Pope, but conciliar power was again limited when the pope declared the Council of Basel heretical.
Council of Ferrara-Florence (#17b) Sept 17, 1437 to January 1939 (Ferrara); January 1439 to Apr. 25, 1442 (Florence); Apr. 25, 1442 to 1445 (Rome) - The Council of Ferrara-Florence was convened for the primary purpose of ending the schism between that church and the Eastern Orthodox Church.
Fifth Lateran Council (#18) May 3, 1512 to Mar. 16, 1517 - The Fifth Lateran Council was convoked for the purpose of reform, but the main causes of the Reformation were left untouched. Its most significant decree was a condemnation of Conciliarism.
Three Western Ecumenical Councils have been held since the Reformation.
Council of Trent (#19) Dec. 13, 1545 to 1563 - The Council of Trent met over a period of 18 years to deal with the Protestant revolt; it was decisively anti-Protestant in its decrees. Trent saw the authority of the church partly in Scripture and partly in tradition and its bishops rejected the teaching of Protestants that humans are justified only by Grace through faith. Dogmatic decisions were passed regarding original sin and justification, the seven Sacraments, and the Mass, and the cult of the saints.
First Vatical Council (#20) Dec. 8, 1869 to Oct. 20, 1870 - The First Vatican Council, convened at Rome in 1869-70, not only continued the attempts to define Roman Catholicism against the rest of ecumenical Christendom, but decreed that--in matters of faith and morals when he speaks officially and with clear intention to do so--the pope is infallible.
Second Vatican Council (#21) Oct. 11, 1962 to Dec. 8, 1965 - The Second Vatican Council (1962-65), which also met in Rome, showed a different outlook. First, it invited observers from Orthodox and Protestant churches; second, the bishops did vote for a principle of collegiality, which gave higher status to their participation. Collegiality, however, did not effectively limit the supremacy of the pope.
Roman Catholic Listing of Ecumenical Councils - At the bottom of this link is a link to detailed information about each council.
Blessings!