Long-range quasi-static gauge-boson interactions lead to anomalous (non-Fermiliquid) behavior of the specific heat in the low-temperature limit of an electron or quark gas with a leading T ln T −1 term. We obtain perturbative results beyond the leading log approximation and find that dynamical screening gives rise to a low-temperature series involving also anomalous fractional powers T (3+2n)/3 . We determine their coefficients in perturbation theory up to and including order T 7/3 and compare with exact numerical results obtained in the large-N f limit of QED and QCD. PACS numbers: 11.10.Wx, 12.38.Mh, 71.45.Gm, 11.15.Pg It has been established long ago [1] in the context of a nonrelativistic electron gas that the only weakly screened low-frequency transverse gauge-boson interactions lead to a qualitative deviation from Fermi liquid behavior. A particular consequence of this is the appearance of an anomalous contribution to the low-temperature limit of entropy and specific heat proportional to αT ln T −1 [1, 2, 3], but it was argued that the effect would be probably too small for experimental detection.More recently, it has been realized that analogous non-Fermi-liquid behavior in ultradegenerate QCD is of central importance to the magnitude of the gap in color superconductivity [4,5,6], and it has been pointed out [7] that the anomalous contributions to the low-temperature specific heat may be of interest in astrophysical systems such as neutron or protoneutron stars, if they involve a normal (non-superconducting) degenerate quark matter component.So far only the coefficient of the αT ln T −1 term in the specific heat has been determined (with Ref.[3] correcting the result of Ref.[1] by a factor of 4), but not the complete argument of the leading logarithm. While the existence of the T ln T −1 term implies that there is a temperature range where the entropy or the specific heat exceeds the ideal-gas value, without knowledge of the constants "under the log" it is impossible to give numerical values for the required temperatures.Furthermore, a quantitative understanding of these anomalous contributions is also of interest with regard to the recent progress made in high-order perturbative calculations of the pressure (free energy) of QCD at nonzero temperature and chemical potential [8], where it has been found that dimensional reduction techniques work remarkably well except for a narrow strip in the T -µ-plane around the T = 0 line.In the present Letter we report the results of a calculation of the low-temperature entropy and specific heat for ultradegenerate QED and QCD which goes beyond the leading log approximation. Besides completing the leading logarithm, we find that for T /µ ≪ g ≪ 1, where g is either the strong or the electromagnetic coupling constant, the higher terms of the low-temperature series involve also anomalous fractional powers T (3+2n)/3 , and we give their coefficients through order T 7/3 . Our starting point is an expression for the thermodynamic potential of QED and QCD