A precise and accurate timescale is critical for calibrating major events in Earth history and testing their spatiotemporal relationships for putative causes. The Newark-Hartford astrochronostratigraphic polarity timescale (APTS) was developed in cyclical lacustrine continental deposits spanning 27 million years of Late Triassic and earliest Jurassic time using the theoretically constant 405 kyr eccentricity cycle linked to gravitational interactions with Jupiter-Venus as a tuning target and provides a major calibration for the early Mesozoic. While this cycle is both unimodal and the most metronomic of the major orbital cycles thought to pace Earth’s climate in numerical solutions, there has been no empirical confirmation of that behavior, given the potential chaotic behavior of the Solar System. An additional criticism of the Newark-Hartford APTS is that it is anchored only at its younger end by U-Pb zircon dates at 201.6 Ma. To test the validity of the dangling APTS and orbital periodicities, we recovered a diagnostic magnetic polarity sequence providing an unambiguous correlation to the APTS in the volcaniclastic-bearing Chinle Formation in drill core PFNP-1A from Petrified Forest National Park (Arizona, US). New U-Pb CA-TIMS detrital zircon dates from the core are indistinguishable from ages predicted by the APTS back to 215 Ma. The APTS is evidently continuous to a small fraction of a remarkably constant 405 kyr orbital eccentricity cycle, thus extending the empirical evidence well beyond theoretical solutions regarded as reliable back to only 50 Ma. The Newark-Hartford APTS becomes the longest directly calibrated polarity sequence and can be used to resolve various Earth history problems, for example, to differentiate provinciality from global temporal patterns in the ecological rise of early dinosaurs.