  Twisted bilayer graphene (TBG) with interlayer twist angles near the magic
angle $\approx 1.08^{\circ}$ hosts flat bands and exhibits correlated states
including Mott-like insulators, superconductivity and magnetism. Here we report
combined temperature-dependent transport measurements of the longitudinal and
Hall resistivities in close to magic-angle TBG. While the observed longitudinal
resistivity follows linear temperature $T$ dependence consistent with previous
reports, the Hall resistance shows an anomalous $T$ dependence with the
cotangent of the Hall angle cot $\Theta{_H} \propto T^2$. Boltzmann theory for
quasiparticle transport predicts that both the resistivity and cot $\Theta{_H}$
should have the same $T$ dependence, contradicting the observed behavior. This
failure of quasiparticle-based theories is reminiscent of other correlated
strange metals such as cuprates.
