This gu appears to belong to the Zhengzhou to Anyang transition (15th-14th century BC).
R. W. Bagley in Shang Ritual Bronzes from the Arthur M. Sackler Collections, Washington D.C. and Cambridge, Massachusetts, 1987, illustrates a series of bronze gu that span this transitional period, pp. 218-9, figs. 25.1-6. In these illustrations one can see the gradual change in the shape from the broader silhouette of the earlier examples, figs. 25.1 and 25.2, to the taller, more slender silhouette of the later examples, figs. 25.5 and 25.6. Fig. 25.3, p. 218, shows line drawings of two gu that were excavated at Hebei Gaocheng Taixicun. The shorter and broader of the two was discovered on a lower stratum than the taller and slightly more slender gu. The decoration on both appears to be somewhat similar to the present vessel, as there is a taotie band on the middle section. While both also have a band of scrolls on the spreading foot, that on the taller (26 cm. high) incorporates eyes, although the scroll ground appears to be much tighter or denser than on the present vessel. Also, on both, the decorative bands are between narrow borders of circles. The author also notes that "at an early stage the gu acquired a slight molding at its foot rim". This can be seen on most of the illustrated gu as well as on the present vessel. All of these vessels, along with the present vessel, share the same large cruciform apertures left by the casting process.
Technical examination report available upon request.